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Querying the database using ADO.NET

This section describes how to create queries to do the following:.

1: Inserting data (ADO.NET)

1.1: Using parameters
1.2: Creating and rolling back transactions

1.2.1: Setting the transaction isolation level

2: Reading data (ADO.Net)
3: Loading data through ADO.Net

3.1: Using the Vertica data adapter
3.2: Using batch inserts and prepared statements
3.3: Streaming data via ADO.NET

3.3.1: Streaming from the client via VerticaCopyStream
3.3.2: Using copy with ADO.NET

This section describes how to create queries to do the following:

Note

The ExecuteNonQuery() method used to query the database returns an int32 with the number of rows affected by the query. The maximum size of an int32 type is a constant and is defined to be 2,147,483,547. If your query returns more results than the int32 max, then ADO.NET throws an exception because of the overflow of the int32 type. However the query is still processed by Vertica even when the reporting of the return value fails. This is a limitation in .NET, as ExecuteNonQuery() is part of the standard ADO.NET interface.

1 - Inserting data (ADO.NET)

Inserting data can done using the VerticaCommand class.

Inserting data can done using the VerticaCommand class. VerticaCommand is an implementation of DbCommand. It allows you to create and send a SQL statement to the database. Use the CommandText method to assign a SQL statement to the command and then execute the SQL by calling the ExecuteNonQuery method. The ExecuteNonQuery method is used for executing statements that do not return result sets.

To insert a single row of data:

Create a connection to the database.

Create a command object using the connection.

VerticaCommand command = _conn.CreateCommand();

Insert data using an INSERT statement. The following is an example of a simple insert. Note that is does not contain a COMMIT statement because the Vertica ADO.NET driver operates in autocommit mode.
```
command.CommandText =
     "INSERT into test values(2, 'username', 'email', 'password')";
```
Execute the query. The rowsAdded variable contains the number of rows added by the insert statement.
```
Int32 rowsAdded = command.ExecuteNonQuery();
```
The ExecuteNonQuery() method returns the number of rows affected by the command for UPDATE, INSERT, and DELETE statements. For all other types of statements it returns -1. If a rollback occurs then it is also set to -1.

Example usage:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using Vertica.Data.VerticaClient;
namespace ConsoleApplication
{
    class Program
    {
        static void Main(string[] args)
        {
            VerticaConnectionStringBuilder builder = new VerticaConnectionStringBuilder();
            builder.Host = "192.168.1.10";
            builder.Database = "VMart";
            builder.User = "dbadmin";
            VerticaConnection _conn = new VerticaConnection(builder.ToString());
            _conn.Open();
        VerticaCommand command = _conn.CreateCommand();
        command.CommandText =
               "INSERT into test values(2, 'username', 'email', 'password')";
        Int32 rowsAdded = command.ExecuteNonQuery();
        Console.WriteLine( rowsAdded + " rows added!");
            _conn.Close();
        }
    }
}

1.1 - Using parameters

You can use parameters to execute similar SQL statements repeatedly and efficiently.

Using parameters

VerticaParameters are an extension of the System.Data.DbParameter base class in ADO.NET and are used to set parameters in commands sent to the server. Use Parameters in all queries (SELECT/INSERT/UPDATE/DELETE) for which the values in the WHERE clause are not static; that is for all queries that have a known set of columns, but whose filter criteria is set dynamically by an application or end user. Using parameters in this way greatly decreases the chances of a SQL injection issue that can occur when simply creating a SQL query from a number of variables.

Parameters require that a valid DbType, VerticaDbType, or System type be assigned to the parameter. See Data types and ADO.NET data types for a mapping of System, Vertica, and DbTypes.

To create a parameter placeholder, place either the at sign (@) or a colon (:) character in front of the parameter name in the actual query string. Do not insert any spaces between the placeholder indicator (@ or :) and the placeholder.

Note

The @ character is the preferred way to identify parameters. The colon (:) character is supported for backward compatibility.

For example, the following typical query uses the string 'MA' as a filter.

SELECT customer_name, customer_address, customer_city, customer_state
FROM customer_dimension WHERE customer_state = 'MA';

Instead, the query can be written to use a parameter. In the following example, the string MA is replaced by the parameter placeholder @STATE.

SELECT customer_name, customer_address, customer_city, customer_state
FROM customer_dimension WHERE customer_state = @STATE;

For example, the ADO.net code for the prior example would be written as:

VerticaCommand command = _conn.CreateCommand();
command.CommandText = “SELECT customer_name, customer_address, customer_city, customer_state
    FROM customer_dimension WHERE customer_state = @STATE”;
command.Parameters.Add(new VerticaParameter( “STATE”, VerticaType.VarChar));
command.Parameters["STATE"].Value = "MA";

Note

Although the VerticaCommand class supports a Prepare() method, you do not need to call the Prepare() method for parameterized statements because Vertica automatically prepares the statement for you.

1.2 - Creating and rolling back transactions

Transactions in Vertica are atomic, consistent, isolated, and durable.

Creating transactions

Transactions in Vertica are atomic, consistent, isolated, and durable. When you connect to a database using the Vertica ADO.NET Driver, the connection is in autocommit mode and each individual query is committed upon execution. You can collect multiple statements into a single transaction and commit them at the same time by using a transaction. You can also choose to rollback a transaction before it is committed if your code determines that a transaction should not commit.

Transactions use the VerticaTransaction object, which is an implementation of DbTransaction. You must associate the transaction with the VerticaCommand object.

The following code uses an explicit transaction to insert one row each into to tables of the VMart schema.

To create a transaction in Vertica using the ADO.NET driver:

Create a connection to the database.

Create a command object using the connection.

VerticaCommand command = _conn.CreateCommand();

Start an explicit transaction, and associate the command with it.

VerticaTransaction txn = _conn.BeginTransaction();
command.Connection = _conn;
command.Transaction = txn;

Execute the individual SQL statements to add rows.

command.CommandText =
     "insert into product_dimension values( ... )";
command.ExecuteNonQuery();
command.CommandText =
     "insert into store_orders_fact values( ... )";

Commit the transaction.
```
txn.Commit();
```

Rolling back transactions

If your code checks for errors, then you can catch the error and rollback the entire transaction.

VerticaTransaction txn = _conn.BeginTransaction();
VerticaCommand command = new
        VerticaCommand("insert into product_dimension values( 838929, 5, 'New item 5' )", _conn);
// execute the insert
command.ExecuteNonQuery();
command.CommandText = "insert into product_dimension values( 838929, 6, 'New item 6' )";
// try insert and catch any errors
bool error = false;
try
{
    command.ExecuteNonQuery();
}
catch (Exception e)
{
    Console.WriteLine(e.Message);
    error = true;
}
if (error)
{
    txn.Rollback();
    Console.WriteLine("Errors. Rolling Back.");
}
else
{
    txn.Commit();
    Console.WriteLine("Queries Successful. Committing.");
}

Commit and rollback example

This example details how you can commit or rollback queries during a transaction.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using Vertica.Data.VerticaClient;
namespace ConsoleApplication
{
    class Program
    {
        static void Main(string[] args)
        {
            VerticaConnectionStringBuilder builder = new VerticaConnectionStringBuilder();
            builder.Host = "192.168.1.10";
            builder.Database = "VMart";
            builder.User = "dbadmin";
            VerticaConnection _conn = new VerticaConnection(builder.ToString());
            _conn.Open();
            bool error = false;
                VerticaCommand command = _conn.CreateCommand();
                VerticaCommand command2 = _conn.CreateCommand();
                VerticaTransaction txn = _conn.BeginTransaction();
                command.Connection = _conn;
                command.Transaction = txn;
                command.CommandText =
                "insert into test values(1, 'test', 'test', 'test' )";
                Console.WriteLine(command.CommandText);
                try
                {
                    command.ExecuteNonQuery();
                }
                catch (Exception e)
                {
                    Console.WriteLine(e.Message);
                    error = true;
                }
                command.CommandText =
                "insert into test values(2, 'ear', 'eye', 'nose', 'extra' )";
                Console.WriteLine(command.CommandText);
                try
                {
                    command.ExecuteNonQuery();
                }
                catch (Exception e)
                {
                    Console.WriteLine(e.Message);
                    error = true;
                }
                if (error)
                {
                    txn.Rollback();
                    Console.WriteLine("Errors. Rolling Back.");
                }
                else
                {
                    txn.Commit();
                    Console.WriteLine("Queries Successful. Committing.");
                }
            _conn.Close();
        }
    }
}

The example displays the following output on the console:

insert into test values(1, 'test', 'test', 'test' )
insert into test values(2, 'ear', 'eye', 'nose', 'extra' )
[42601]ERROR: INSERT has more expressions than target columns
Errors. Rolling Back.

1.2.1 - Setting the transaction isolation level

You can set the transaction isolation level on a per-connection and per-transaction basis.

You can set the transaction isolation level on a per-connection and per-transaction basis. See Transaction for an overview of the transaction isolation levels supported in Vertica. To set the default transaction isolation level for a connection, use the IsolationLevel keyword in the VerticaConnectionStringBuilder string (see Connection String Keywords for details). To set the isolation level for an individual transaction, pass the isolation level to the VerticaConnection.BeginTransaction() method call to start the transaction.

To set the isolation level on a connection-basis:

Use the VerticaConnectionStringBuilder to build the connection string.

Provide a value for the IsolationLevel builder string. It can take one of two values: IsolationLevel.ReadCommited (default) or IsolationLevel.Serializeable. For example:

    VerticaConnectionStringBuilder builder = new VerticaConnectionStringBuilder();
    builder.Host = "192.168.1.100";
    builder.Database = "VMart";
    builder.User = "dbadmin";
    builder.IsolationLevel = System.Data.IsolationLevel.Serializeable
    VerticaConnection _conn1 = new VerticaConnection(builder.ToString());
    _conn1.Open();

To set the isolation level on a transaction basis:

Set the IsolationLevel on the BeginTransaction method, for example

VerticaTransaction txn = _conn.BeginTransaction(IsolationLevel.Serializable);

Example usage:

The following example demonstrates:

getting the connection's transaction isolation level.
setting the connection's isolation level using connection property.
setting the transaction isolation level for a new transaction.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
Vertica.Data.VerticaClient;
namespace ConsoleApplication
{
    class Program
    {
        static void Main(string[] args)
        {
            VerticaConnectionStringBuilder builder = new VerticaConnectionStringBuilder();
            builder.Host = "192.168.1.10";
            builder.Database = "VMart";
            builder.User = "dbadmin";
            VerticaConnection _conn1 = new VerticaConnection(builder.ToString());
             _conn1.Open();
            VerticaTransaction txn1 = _conn1.BeginTransaction();
            Console.WriteLine("\n Transaction 1 Transaction Isolation Level: " +
             txn1.IsolationLevel.ToString());
            txn1.Rollback();
            VerticaTransaction txn2 = _conn1.BeginTransaction(IsolationLevel.Serializable);
            Console.WriteLine("\n Transaction 2 Transaction Isolation Level: " +
             txn2.IsolationLevel.ToString());
            txn2.Rollback();
            VerticaTransaction txn3 = _conn1.BeginTransaction(IsolationLevel.ReadCommitted);
            Console.WriteLine("\n Transaction 3 Transaction Isolation Level: " +
             txn3.IsolationLevel.ToString());
            _conn1.Close();
        }
    }
}

When run, the example code prints the following to the system console:

 Transaction 1 Transaction Isolation Level: ReadCommitted
 Transaction 2 Transaction Isolation Level: Serializable
 Transaction 3 Transaction Isolation Level: ReadCommitted

2 - Reading data (ADO.Net)

To read data from the database use VerticaDataReader, an implementation of DbDataReader.

To read data from the database use VerticaDataReader, an implementation of DbDataReader. This implementation is useful for moving large volumes of data quickly off the server where it can be run through analytic applications.

Note

A VerticaCommand cannot execute anything else while it has an open VerticaDataReader associated with it. To execute something else, close the data reader or use a different VerticaCommand object.

To read data from the database using VerticaDataReader:

Create a connection to the database.

Create a command object using the connection.

    VerticaCommand command = _conn.CreateCommand();

Create a query. This query works with the example VMart database.

        command.CommandText =
        "SELECT fat_content, product_description " +
        "FROM (SELECT DISTINCT fat_content, product_description" +
        "      FROM product_dimension " +
        "      WHERE department_description " +        "      IN ('Dairy') " +
        "      ORDER BY fat_content) AS food " +
        "LIMIT 10;";

Execute the reader to return the results from the query. The following command calls the ExecuteReader method of the VerticaCommand object to obtain the VerticaDataReader object.
```
VerticaDataReader dr = command.ExecuteReader();
```

Read the data. The data reader returns results in a sequential stream. Therefore, you must read data from tables row-by-row. The following example uses a while loop to accomplish this:

 Console.WriteLine("\n\n Fat Content\t  Product Description");
     Console.WriteLine("------------\t  -------------------");
     int rows = 0;
     while (dr.Read())
     {
        Console.WriteLine("     " + dr[0] + "    \t  " + dr[1]);
        ++rows;
     }
     Console.WriteLine("------------\n  (" + rows + " rows)\n");

When you're finished, close the data reader to free up resources.
```
    dr.Close();
```

Example usage:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using Vertica.Data.VerticaClient;
namespace ConsoleApplication
{
    class Program
    {
        static void Main(string[] args)
        {
            VerticaConnectionStringBuilder builder = new VerticaConnectionStringBuilder();
            builder.Host = "192.168.1.10";
            builder.Database = "VMart";
            builder.User = "dbadmin";
            VerticaConnection _conn = new VerticaConnection(builder.ToString());
            _conn.Open();
        VerticaCommand command = _conn.CreateCommand();
            command.CommandText =
                "SELECT fat_content, product_description " +
                "FROM (SELECT DISTINCT fat_content, product_description" +
                "      FROM product_dimension " +
                "      WHERE department_description " +
                "      IN ('Dairy') " +
                "      ORDER BY fat_content) AS food " +
                "LIMIT 10;";
          VerticaDataReader dr = command.ExecuteReader();

         Console.WriteLine("\n\n Fat Content\t  Product Description");
         Console.WriteLine("------------\t  -------------------");
         int rows = 0;
         while (dr.Read())
         {
                Console.WriteLine("     " + dr[0] + "    \t  " + dr[1]);
                ++rows;
         }
         Console.WriteLine("------------\n  (" + rows + " rows)\n");
              dr.Close();
            _conn.Close();
        }
    }
}

3 - Loading data through ADO.Net

This section details the different ways that you can load data in Vertica using the ADO.NET client driver:.

This section details the different ways that you can load data in Vertica using the ADO.NET client driver:

3.1 - Using the Vertica data adapter

The Vertica data adapter (VerticaDataAdapter) enables a client to exchange data between a data set and a Vertica database.

The Vertica data adapter (VerticaDataAdapter) enables a client to exchange data between a data set and a Vertica database. It is an implementation of DbDataAdapter. You can use VerticaDataAdapter to simply read data, or, for example, read data from a database into a data set, and then write changed data from the data set back to the database.

Batching updates

When using the Update() method to update a dataset, you can optionally use the UpdateBatchSize() method prior to calling Update() to reduce the number of times the client communicates with the server to perform the update. The default value of UpdateBatchSize is 1. If you have multiple rows.Add() commands for a data set, then you can change the batch size to an optimal size to speed up the operations your client must perform to complete the update.

Reading data from Vertica using the data adapter:

The following example details how to perform a select query on the VMart schema and load the result into a DataTable, then output the contents of the DataTable to the console.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Data.SqlClient;
Vertica.Data.VerticaClient;
namespace ConsoleApplication
{
    class Program
    {
        static void Main(string[] args)
        {
            VerticaConnectionStringBuilder builder = new VerticaConnectionStringBuilder();
            builder.Host = "192.168.1.10";
            builder.Database = "VMart";
            builder.User = "dbadmin";
            VerticaConnection _conn = new VerticaConnection(builder.ToString());
            _conn.Open();

            // Try/Catch any exceptions
                   try
            {
                using (_conn)
                {
                    // Create the command
                    VerticaCommand command = _conn.CreateCommand();
                    command.CommandText = "select product_key, product_description " +
                        "from product_dimension where product_key < 10";

                        // Associate the command with the connection
                        command.Connection = _conn;

                        // Create the DataAdapter
                        VerticaDataAdapter adapter = new VerticaDataAdapter();
                        adapter.SelectCommand = command;

                        // Fill the DataTable
                        DataTable table = new DataTable();
                        adapter.Fill(table);

                        //  Display each row and column value.
                        int i = 1;
                        foreach (DataRow row in table.Rows)
                        {
                            foreach (DataColumn column in table.Columns)
                            {
                                Console.Write(row[column] + "\t");
                            }
                            Console.WriteLine();
                            i++;
                        }
                    Console.WriteLine(i + " rows returned.");
                }
            }
            catch (Exception e)
            {
                Console.WriteLine(e.Message);
            }
            _conn.Close();
        }
    }
}

Reading data from Vertica into a data set and changing data:

The following example shows how to use a data adapter to read from and insert into a dimension table of the VMart schema.


using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Data.SqlClient;
using Vertica.Data.VerticaClient
namespace ConsoleApplication
{
    class Program
    {
        static void Main(string[] args)
        {
            VerticaConnectionStringBuilder builder = new VerticaConnectionStringBuilder();
            builder.Host = "192.168.1.10";
            builder.Database = "VMart";
            builder.User = "dbadmin";
            VerticaConnection _conn = new VerticaConnection(builder.ToString());
            _conn.Open();

                  // Try/Catch any exceptions
                    try
            {
                using (_conn)
                {

                            //Create a data adapter object using the connection
                            VerticaDataAdapter da = new VerticaDataAdapter();

                            //Create a select statement that retrieves data from the table
                            da.SelectCommand = new
                        VerticaCommand("select * from product_dimension where product_key < 10",
                        _conn);
                            //Set up the insert command for the data adapter, and bind variables for some of the columns
                            da.InsertCommand = new
                        VerticaCommand("insert into product_dimension values( :key, :version, :desc )",
                        _conn);
                    da.InsertCommand.Parameters.Add(new VerticaParameter("key", VerticaType.BigInt));
                    da.InsertCommand.Parameters.Add(new VerticaParameter("version", VerticaType.BigInt));
                    da.InsertCommand.Parameters.Add(new VerticaParameter("desc", VerticaType.VarChar));
                    da.InsertCommand.Parameters[0].SourceColumn = "product_key";
                    da.InsertCommand.Parameters[1].SourceColumn = "product_version";
                    da.InsertCommand.Parameters[2].SourceColumn = "product_description";
                    da.TableMappings.Add("product_key", "product_key");
                    da.TableMappings.Add("product_version", "product_version");
                    da.TableMappings.Add("product_description", "product_description");

                            //Create and fill a Data set for this dimension table, and get the resulting DataTable.
                            DataSet ds = new DataSet();
                    da.Fill(ds, 0, 0, "product_dimension");
                    DataTable dt = ds.Tables[0];

                            //Bind parameters and add two rows to the table.
                            DataRow dr = dt.NewRow();
                    dr["product_key"] = 838929;
                    dr["product_version"] = 5;
                    dr["product_description"] = "New item 5";
                    dt.Rows.Add(dr);
                    dr = dt.NewRow();
                    dr["product_key"] = 838929;
                    dr["product_version"] = 6;
                    dr["product_description"] = "New item 6";
                    dt.Rows.Add(dr);
                    //Extract the changes for the added rows.
                            DataSet ds2 = ds.GetChanges();

                            //Send the modifications to the server.
                            int updateCount = da.Update(ds2, "product_dimension");

                           //Merge the changes into the original Data set, and mark it up to date.
                            ds.Merge(ds2);
                    ds.AcceptChanges();
                    Console.WriteLine(updateCount + " updates made!");
                }
            }
            catch (Exception e)
            {
                Console.WriteLine(e.Message);
            }
            _conn.Close();
        }
    }
}

3.2 - Using batch inserts and prepared statements

You can load data in batches using a prepared statement with parameters.

You can load data in batches using a prepared statement with parameters. You can also use transactions to rollback the batch load if any errors are encountered.

If you are loading large batches of data (more than 100MB), then consider using a direct batch insert.

The following example details using data contained in arrays, parameters, and a transaction to batch load data.

The test table used in the example is created with the command:

=> CREATE TABLE test (id INT, username VARCHAR(24), email VARCHAR(64), password VARCHAR(8));

Example batch insert using parameters and transactions


using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using Vertica.Data.VerticaClient;
namespace ConsoleApplication
{
    class Program
    {
        static void Main(string[] args)
        {
            VerticaConnectionStringBuilder builder = new VerticaConnectionStringBuilder();
            builder.Host = "192.168.1.10";
            builder.Database = "VMart";
            builder.User = "dbadmin";
            VerticaConnection _conn = new VerticaConnection(builder.ToString());
            _conn.Open();
            // Create arrays for column data
                    int[] ids = {1, 2, 3, 4};
            string[] usernames = {"user1", "user2", "user3", "user4"};
            string[] emails = { "user1@example.com", "user2@example.com","user3@example.com","user4@example.com" };
            string[] passwords = { "pass1", "pass2", "pass3", "pass4" };
            // create counters for accepted and rejected rows
                    int rows = 0;
            int rejRows = 0;
            bool error = false;
            // Create the transaction
                    VerticaTransaction txn = _conn.BeginTransaction();
            // Create the parameterized query and assign parameter types
                    VerticaCommand command = _conn.CreateCommand();
            command.CommandText = "insert into TEST values (@id, @username, @email, @password)";
            command.Parameters.Add(new VerticaParameter("id", VerticaType.BigInt));
            command.Parameters.Add(new VerticaParameter("username", VerticaType.VarChar));
            command.Parameters.Add(new VerticaParameter("email", VerticaType.VarChar));
            command.Parameters.Add(new VerticaParameter("password", VerticaType.VarChar));
            // Prepare the statement
                    command.Prepare();

                    // Loop through the column arrays and insert the data
                    for (int i = 0; i < ids.Length; i++)            {
                command.Parameters["id"].Value = ids[i];
                command.Parameters["username"].Value = usernames[i];
                command.Parameters["email"].Value = emails[i];
                command.Parameters["password"].Value = passwords[i];
                try
                {
                    rows += command.ExecuteNonQuery();
                }
                catch (Exception e)
                {
                    Console.WriteLine("\nInsert failed - \n  " + e.Message + "\n");
                    ++rejRows;
                    error = true;
                }
            }
            if (error)
            {
                // Roll back if errors
                        Console.WriteLine("Errors. Rolling Back Transaction.");
                Console.WriteLine(rejRows + " rows rejected.");
                txn.Rollback();
            }
            else
            {
                // Commit if no errors
                        Console.WriteLine("No Errors. Committing Transaction.");
                txn.Commit();
                Console.WriteLine("Inserted " + rows + " rows. ");
            }
            _conn.Close();
        }
    }
}

3.3 - Streaming data via ADO.NET

There are two options to stream data from a file on the client to your Vertica database through ADO.NET:.

There are two options to stream data from a file on the client to your Vertica database through ADO.NET:

Use the VerticaCopyStream ADO.NET class to stream data in an object-oriented manner
Execute a COPY LOCAL SQL statement to stream the data

The topics in this section explain how to use these options.

3.3.1 - Streaming from the client via VerticaCopyStream

The VerticaCopyStream class lets you stream data from the client system to a Vertica database.

The VerticaCopyStream class lets you stream data from the client system to a Vertica database. It lets you use the SQL COPY statement directly without having to copy the data to a host in the database cluster first by substituting one or more data stream(s) for STDIN.

Notes:

Use Transactions and disable auto commit on the copy command for better performance.
Disable auto commit using the copy command with the 'no commit' modifier. You must explicitly disable commits. Enabling transactions does not disable autocommit when using VerticaCopyStream.
The copy command used with VerticaCopyStream uses copy syntax.
VerticaCopyStream.rejects is zeroed every time execute is called. If you want to capture the number of rejects, assign the value of VerticaCopyStream.rejects to another variable before calling execute again.
You can add multiple streams using multiple AddStream() calls.

Example usage:

The following example demonstrates using VerticaCopyStream to copy a file stream into Vertica.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.IO;
using Vertica.Data.VerticaClient;
namespace ConsoleApplication
{
    class Program
    {
        static void Main(string[] args)
        {
            // Configure connection properties
                    VerticaConnectionStringBuilder builder = new VerticaConnectionStringBuilder();
                builder.Host = "192.168.1.10";
            builder.Database = "VMart";
            builder.User = "dbadmin";
            //open the connection
            VerticaConnection _conn = new VerticaConnection(builder.ToString());
            _conn.Open();
            try
            {
                using (_conn)
                {
                    // Start a transaction
                            VerticaTransaction txn = _conn.BeginTransaction();

                            // Create a table for this example
                            VerticaCommand command = new VerticaCommand("DROP TABLE IF EXISTS copy_table", _conn);
                command.ExecuteNonQuery();
                    command.CommandText = "CREATE TABLE copy_table (Last_Name char(50), "
                                    + "First_Name char(50),Email char(50), "
                                    + "Phone_Number char(15))";
                    command.ExecuteNonQuery();
                    // Create a new filestream from the data file
                            string filename = "C:/customers.txt";
                 Console.WriteLine("\n\nLoading File: " + filename);
                    FileStream inputfile = File.OpenRead(filename);
                    // Define the copy command
                            string copy = "copy copy_table from stdin record terminator E'\n' delimiter '|'" + " enforcelength "
                        + " no commit";
                    // Create a new copy stream instance with the connection and copy statement
                            VerticaCopyStream vcs = new VerticaCopyStream(_conn, copy);

                            // Start the VerticaCopyStream process
                            vcs.Start();
                            // Add the file stream
                            vcs.AddStream(inputfile, false);

                            // Execute the copy
                            vcs.Execute();

                            // Finish stream and write out the list of inserted and rejected rows
                            long rowsInserted = vcs.Finish();
                IList<long> rowsRejected = vcs.Rejects;
                // Does not work when rejected or exceptions defined
                    Console.WriteLine("Number of Rows inserted: " + rowsInserted);
                    Console.WriteLine("Number of Rows rejected: " + rowsRejected.Count);
                    if (rowsRejected.Count > 0)
                    {
                        for (int i = 0; i < rowsRejected.Count; i++)
                        {
                            Console.WriteLine("Rejected row #{0} is row {1}", i, rowsRejected[i]);
                        }
                    }

                            // Commit the changes
                            txn.Commit();
            }
            }
            catch (Exception e)
            {
                Console.WriteLine(e.Message);
            }


                    //close the connection
                    _conn.Close();
    }
    }
}

3.3.2 - Using copy with ADO.NET

To use COPY with ADO.NET, just execute a COPY statement and the path to the source file on the client system.

To use COPY with ADO.NET, just execute a COPY statement and the path to the source file on the client system. This method is simpler than using the VerticaCopyStream class. However, you may prefer using VerticaCopyStream if you have many files to copy to the database or if your data comes from a source other than a local file (streamed over a network connection, for example).

The following example code demonstrates using COPY to copy a file from the client to the database. It is the same as the code shown in Bulk Loading Using the COPY Statement and the path to the data file is on the client system, rather than on the server.

To load data that is stored on a database node, use a VerticaCommand object to create a COPY command:

Create a connection to the database through the node on which the data file is stored.

Create a command object using the connection.

VerticaCommand command = _conn.CreateCommand();

Copy data. The following is an example of using the COPY command to load data. It uses the LOCAL modifier to copy a file local to the client issuing the command.

command.CommandText = "copy lcopy_table from '/home/dbadmin/customers.txt'"
  + " record terminator E'\n' delimiter '|'"
  + " enforcelength ";

Int32 insertedRows = command.ExecuteNonQuery();
Console.WriteLine(insertedRows + " inserted.");

Example usage:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.IO;
using Vertica.Data.VerticaClient;
namespace ConsoleApplication
{
    class Program
    {
        static void Main(string[] args)
        {
            // Configure connection properties
            VerticaConnectionStringBuilder builder = new VerticaConnectionStringBuilder();
     builder.Host = "192.168.1.10";
        builder.Database = "VMart";
        builder.User = "dbadmin";

                   // Open the connection
                    VerticaConnection _conn = new VerticaConnection(builder.ToString());
            _conn.Open();
            try
            {
                using (_conn)
                {

                            // Start a transaction
                            VerticaTransaction txn = _conn.BeginTransaction();

                            // Create a table for this example
                            VerticaCommand command = new VerticaCommand("DROP TABLE IF EXISTS lcopy_table", _conn);
                    command.ExecuteNonQuery();
                    command.CommandText = "CREATE TABLE IF NOT EXISTS lcopy_table (Last_Name char(50), "
                                    + "First_Name char(50),Email char(50), "
                                    + "Phone_Number char(15))";
                    command.ExecuteNonQuery();
                    // Define the copy command
                            command.CommandText = "copy lcopy_table from '/home/dbadmin/customers.txt'"
            + " record terminator E'\n' delimiter '|'"
                        + " enforcelength "
                + " no commit";
                            // Execute the copy
        Int32 insertedRows = command.ExecuteNonQuery();
Console.WriteLine(insertedRows + " inserted.");
                            // Commit the changes
                            txn.Commit();
                }
            }
            catch (Exception e)
            {
                Console.WriteLine("Exception: " + e.Message);
            }


                    // Close the connection
                    _conn.Close();
        }
    }
}

Querying the database using ADO.NET

Note

1 - Inserting data (ADO.NET)

To insert a single row of data:

Example usage:

1.1 - Using parameters

Using parameters

Note

Note

1.2 - Creating and rolling back transactions

Creating transactions

To create a transaction in Vertica using the ADO.NET driver:

Rolling back transactions

Commit and rollback example

See also

1.2.1 - Setting the transaction isolation level

To set the isolation level on a connection-basis:

To set the isolation level on a transaction basis:

Example usage:

2 - Reading data (ADO.Net)

Note

To read data from the database using VerticaDataReader:

Example usage:

3 - Loading data through ADO.Net

3.1 - Using the Vertica data adapter

Batching updates

Reading data from Vertica using the data adapter:

Reading data from Vertica into a data set and changing data:

3.2 - Using batch inserts and prepared statements

Example batch insert using parameters and transactions

3.3 - Streaming data via ADO.NET

3.3.1 - Streaming from the client via VerticaCopyStream

Example usage:

3.3.2 - Using copy with ADO.NET

Example usage: