OpenText Analytics Database 26.2.x – Working with spatial objects from client applications

Data-Analysis: Using LONG VARCHAR and LONG VARBINARY data types with ODBC

Mon, 01 Jan 0001 00:00:00 +0000

The ODBC drivers support the LONG VARCHAR and LONG VARBINARY data types similarly to VARCHAR and VARBINARY data types. When binding input or output parameters to a LONG VARCHAR or LONG VARBINARY column in a query, use the SQL_LONGVARCHAR and SQL_LONGVARBINARY constants to set the column's data type. For example, to bind an input parameter to a LONG VARCHAR column, you would use a statement that looks like this:

rc = SQLBindParameter(hdlStmt, 1, SQL_PARAM_INPUT, SQL_C_CHAR, SQL_LONGVARCHAR,
             80000, 0, (SQLPOINTER)myLongString, sizeof(myLongString), NULL);

Note

Do not use inefficient encoding formats for LONG VARBINARY and LONG VARCHAR values. OpenText™ Analytics Database cannot load encoded values larger than 32MB, even if the decoded value is less than 32 MB in size. For example, the database returns an error if you attempt to load a 32MB LONG VARBINARY value encoded in octal format, since the octal encoding quadruples the size of the value (each byte is converted into a backslash followed by three digits).

Data-Analysis: Using LONG VARCHAR and LONG VARBINARY data types with JDBC

Mon, 01 Jan 0001 00:00:00 +0000

Using LONG VARCHAR and LONG VARBINARY data types in a JDBC client application is similar to using VARCHAR and VARBINARY data types. The JDBC driver transparently handles the conversion (for example, between a Java String object and a LONG VARCHAR).

The following example code demonstrates inserting and retrieving a LONG VARCHAR string. It uses the JDBC Types class to determine the data type of the string returned by the database, although it does not actually need to know whether the database column is a LONG VARCHAR or just a VARCHAR in order to retrieve the value.

import java.sql.*;
import java.util.Properties;

public class LongVarcharExample {
    public static void main(String[] args) {
        try {
            Class.forName("com.vertica.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            System.err.println("Could not find the JDBC driver class.");
            e.printStackTrace();
            return;
        }
        Properties myProp = new Properties();
        myProp.put("user", "ExampleUser");
        myProp.put("password", "password123");
        Connection conn;
        try {
            conn = DriverManager.getConnection(
                            "jdbc:vertica://VerticaHost:5433/ExampleDB",
                            myProp);
            // establish connection and make a table for the data.
            Statement stmt = conn.createStatement();

            // How long we want the example string to be. This is
            // larger than can fit into a traditional VARCHAR (which is limited
            // to 65000.
            int length = 100000;

            // Create a table with a LONG VARCHAR column that can store
            // the string we want to insert.
            stmt.execute("DROP TABLE IF EXISTS longtable CASCADE");
            stmt.execute("CREATE TABLE longtable (text LONG VARCHAR(" + length
                            + "))");
            // Build a long string by appending an integer to a string builder
            // until we hit the size limit. Will result in a string
            // containing 01234567890123....
            StringBuilder sb = new StringBuilder(length);
            for (int i = 0; i < length; i++)
            {
                sb.append(i % 10);
            }
            String value = sb.toString();

            System.out.println("String value is " + value.length() +
                            " characters long.");

            // Create the prepared statement
            PreparedStatement pstmt = conn.prepareStatement(
                            "INSERT INTO longtable (text)" +
                            " VALUES(?)");
            try {
                // Insert LONG VARCHAR value
                System.out.println("Inserting LONG VARCHAR value");
                pstmt.setString(1, value);
                pstmt.addBatch();
                pstmt.executeBatch();

                // Query the table we created to get the value back.
                ResultSet rs = null;
                rs = stmt.executeQuery("SELECT * FROM longtable");

                // Get metadata about the result set.
                ResultSetMetaData rsmd = rs.getMetaData();
                // Print the type of the first column. Should be
                // LONG VARCHAR. Also check it against the Types class, to
                // recognize it programmatically.
                System.out.println("Column #1 data type is: " +
                                rsmd.getColumnTypeName(1));
                if (rsmd.getColumnType(1) == Types.LONGVARCHAR) {
                    System.out.println("It is a LONG VARCHAR");
                } else {
                    System.out.println("It is NOT a LONG VARCHAR");
                }

                // Print out the string length of the returned value.
                while (rs.next()) {
                    // Use the same getString method to get the value that you
                    // use to get the value of a VARCHAR.
                    System.out.println("Returned string length: " +
                                    rs.getString(1).length());
                }
            } catch (SQLException e) {
                System.out.println("Error message: " + e.getMessage());
                return; // Exit if there was an error
            }
            // Cleanup
            conn.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

Note

Data-Analysis: Using GEOMETRY and GEOGRAPHY data types in ODBC

Mon, 01 Jan 0001 00:00:00 +0000

GEOMETRY and GEOGRAPHY data types are backed by LONG VARBINARY native types and ODBC client applications treat them as binary data. However, these data types have a format that is unique to OpenText™ Analytics Database. To manipulate this data in your C++ application, you must use the functions in the database that convert them to a recognized format.

To convert a WKT or WKB to the GEOMETRY or GEOGRAPHY format, use one of the following SQL functions:

ST_GeographyFromText—Converts a WKT to a GEOGRAPHY type.
ST_GeographyFromWKB—Converts a WKB to a GEOGRAPHY type.
ST_GeomFromText—Converts a WKT to a GEOMETRY type.
ST_GeomFromWKB—Converts a WKB to GEOMETRY type.

To convert a GEOMETRY or GEOGRAPHY object to its corresponding WKT or WKB, use one of the following SQL functions:

ST_AsText—Converts a GEOMETRY or GEOGRAPHY object to a WKT, returns a LONGVARCHAR.
ST_AsBinary—Converts a GEOMETRY or GEOGRAPHY object to a WKB, returns a LONG VARBINARY.

The following code example converts WKT data into GEOMETRY data using ST_GeomFromText and stores it in a table. Later, this example retrieves the GEOMETRY data from the table and converts it to WKT and WKB format using ST_AsText and ST_AsBinary.

// Compile on Linux using:
//  g++ -g -I/opt/vertica/include -L/opt/vertica/lib64 -lodbc -o SpatialData SpatialData.cpp
// Some standard headers
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <sstream>
// Only needed for Windows clients
// #include <windows.h>
// Standard ODBC headers
#include <sql.h>
#include <sqltypes.h>
#include <sqlext.h>
// Helper function to print SQL error messages.
template <typename HandleT>
void reportError(int handleTypeEnum, HandleT hdl)
{
    // Get the status records.
    SQLSMALLINT   i, MsgLen;
    SQLRETURN     ret2;
    SQLCHAR       SqlState[6], Msg[SQL_MAX_MESSAGE_LENGTH];
    SQLINTEGER    NativeError;
    i = 1;
    printf("\n");
    while ((ret2 = SQLGetDiagRec(handleTypeEnum, hdl, i, SqlState, &NativeError,
                                Msg, sizeof(Msg), &MsgLen)) != SQL_NO_DATA) {
        printf("error record %d\n", i);
        printf("sqlstate: %s\n", SqlState);
        printf("detailed msg: %s\n", Msg);
        printf("native error code: %d\n\n", NativeError);
        i++;
    }
    exit(EXIT_FAILURE); // bad form... but Ok for this demo
}
int main()
{
    // Set up the ODBC environment
    SQLRETURN ret;
    SQLHENV hdlEnv;
    ret = SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &hdlEnv);
    assert(SQL_SUCCEEDED(ret));
    // Tell ODBC that the application uses ODBC 3.
    ret = SQLSetEnvAttr(hdlEnv, SQL_ATTR_ODBC_VERSION,
        (SQLPOINTER) SQL_OV_ODBC3, SQL_IS_UINTEGER);
    assert(SQL_SUCCEEDED(ret));
    // Allocate a database handle.
    SQLHDBC hdlDbc;
    ret = SQLAllocHandle(SQL_HANDLE_DBC, hdlEnv, &hdlDbc);
    assert(SQL_SUCCEEDED(ret));
    // Connect to the database
    printf("Connecting to database.\n");
    const char *dsnName = "ExampleDB";
    const char* userID = "dbadmin";
    const char* passwd = "password123";
    ret = SQLConnect(hdlDbc, (SQLCHAR*)dsnName,
        SQL_NTS,(SQLCHAR*)userID,SQL_NTS,
        (SQLCHAR*)passwd, SQL_NTS);
    if(!SQL_SUCCEEDED(ret)) {
        printf("Could not connect to database.\n");
        reportError<SQLHDBC>(SQL_HANDLE_DBC, hdlDbc);

    } else {
        printf("Connected to database.\n");
    }

    // Disable AUTOCOMMIT
    ret = SQLSetConnectAttr(hdlDbc, SQL_ATTR_AUTOCOMMIT, SQL_AUTOCOMMIT_OFF,
        SQL_NTS);

    // Set up a statement handle
    SQLHSTMT hdlStmt;
    SQLAllocHandle(SQL_HANDLE_STMT, hdlDbc, &hdlStmt);

    // Drop any previously defined table.
    ret = SQLExecDirect(hdlStmt, (SQLCHAR*)"DROP TABLE IF EXISTS polygons",
        SQL_NTS);
    if (!SQL_SUCCEEDED(ret)) {reportError<SQLHDBC>(SQL_HANDLE_STMT, hdlStmt);}

    // Run query to create a table to hold a geometry.
    ret = SQLExecDirect(hdlStmt,
        (SQLCHAR*)"CREATE TABLE polygons(id INTEGER PRIMARY KEY, poly GEOMETRY);",
        SQL_NTS);
    if (!SQL_SUCCEEDED(ret)) {reportError<SQLHDBC>(SQL_HANDLE_STMT, hdlStmt);}

    // Create the prepared statement. This will insert data into the
    // table we created above. It uses the ST_GeomFromText function to convert the
    // string-formatted polygon definition to a GEOMETRY datat type.
    printf("Creating prepared statement\n");
    ret = SQLPrepare (hdlStmt,
        (SQLTCHAR*)"INSERT INTO polygons(id, poly) VALUES(?, ST_GeomFromText(?))",
        SQL_NTS) ;
    if (!SQL_SUCCEEDED(ret)) {reportError<SQLHDBC>(SQL_HANDLE_STMT, hdlStmt);}

    SQLINTEGER id = 0;
    int numBatches = 5;
    int rowsPerBatch = 10;

    // Polygon definition as a string.
    char polygon[] = "polygon((1 1, 1 2, 2 2, 2 1, 1 1))";
    // Bind variables to the parameters in the prepared SQL statement
    ret = SQLBindParameter(hdlStmt, 1, SQL_PARAM_INPUT, SQL_C_LONG, SQL_INTEGER,
        0, 0, &id, 0 , NULL);
    if (!SQL_SUCCEEDED(ret)) {reportError<SQLHDBC>(SQL_HANDLE_STMT,hdlStmt);}
    // Bind polygon string to the geometry column
    SQLBindParameter(hdlStmt, 2, SQL_PARAM_INPUT, SQL_C_CHAR, SQL_LONGVARCHAR,
        strlen(polygon), 0, (SQLPOINTER)polygon, strlen(polygon), NULL);
     if (!SQL_SUCCEEDED(ret)) {reportError<SQLHDBC>(SQL_HANDLE_STMT,hdlStmt);}
    // Execute the insert
    ret = SQLExecute(hdlStmt);
    if(!SQL_SUCCEEDED(ret)) {
       reportError<SQLHDBC>(SQL_HANDLE_STMT, hdlStmt);
    }  else {
        printf("Executed batch.\n");
    }

    // Commit the transaction
    printf("Committing transaction\n");
    ret = SQLEndTran(SQL_HANDLE_DBC, hdlDbc, SQL_COMMIT);
    if(!SQL_SUCCEEDED(ret)) {
        reportError<SQLHDBC>(SQL_HANDLE_STMT, hdlStmt);
    }  else {
        printf("Committed transaction\n");
    }
    // Now, create a query to retrieve the geometry.
    ret = SQLAllocHandle(SQL_HANDLE_STMT, hdlDbc, &hdlStmt);
    if (!SQL_SUCCEEDED(ret)) {reportError<SQLHDBC>(SQL_HANDLE_STMT, hdlStmt);}
    printf("Getting data from table.\n");
    // Execute a query to get the id, raw geometry data, and
    // the geometry data as a string. Uses the ST_AsText SQL function to
    // format raw data back into a string polygon definition
    ret = SQLExecDirect(hdlStmt,
        (SQLCHAR*)"select id,ST_AsBinary(poly),ST_AsText(poly) from polygons ORDER BY id;",
        SQL_NTS);
    if (!SQL_SUCCEEDED(ret)) {reportError<SQLHDBC>(SQL_HANDLE_STMT,hdlStmt);}

    SQLINTEGER idval;
    // 10MB buffer to hold the raw data from the geometry (10Mb is the maximum
    // length of a GEOMETRY)
    SQLCHAR* polygonval = (SQLCHAR*)malloc(10485760);
    SQLLEN polygonlen, polygonstrlen;
    // Buffer to hold a LONGVARCHAR that can result from converting the
    // geometry to a string.
    SQLTCHAR* polygonstr = (SQLTCHAR*)malloc(33554432);

    // Get the results of the query and print each row.
    do {
        ret = SQLFetch(hdlStmt);
        if (SQL_SUCCEEDED(ret)) {
            // ID column
            ret = SQLGetData(hdlStmt, 1, SQL_C_LONG, &idval, 0, NULL);
            if (!SQL_SUCCEEDED(ret)) {reportError<SQLHDBC>(SQL_HANDLE_STMT, hdlStmt);}
            printf("id: %d\n",idval);
            // The WKB format geometry data
            ret = SQLGetData(hdlStmt, 2, SQL_C_BINARY, polygonval, 10485760,
                &polygonlen);
            if (!SQL_SUCCEEDED(ret)) {reportError<SQLHDBC>(SQL_HANDLE_STMT, hdlStmt);}
            printf("Polygon in WKB format: ");
            // Print each byte of polygonval buffer in hex format.
            for (int z = 0; z < polygonlen; z++)
                printf("%02x ",polygonval[z]);
            printf("\n");
            // Geometry data formatted as a string.
            ret = SQLGetData(hdlStmt, 3, SQL_C_TCHAR, polygonstr, 33554432, &polygonstrlen);
            if (!SQL_SUCCEEDED(ret)) {reportError<SQLHDBC>(SQL_HANDLE_STMT, hdlStmt);}
            printf("Polygon in WKT format: %s\n", polygonstr);
        }
    } while(SQL_SUCCEEDED(ret));


    free(polygonval);
    free(polygonstr);
    // Clean up
    printf("Free handles.\n");
    ret = SQLFreeHandle(SQL_HANDLE_STMT, hdlStmt);
    if (!SQL_SUCCEEDED(ret)) {reportError<SQLHDBC>(SQL_HANDLE_STMT, hdlStmt);}
    ret = SQLFreeHandle(SQL_HANDLE_DBC, hdlDbc);
    if (!SQL_SUCCEEDED(ret)) {reportError<SQLHDBC>(SQL_HANDLE_STMT, hdlStmt);}
    ret = SQLFreeHandle(SQL_HANDLE_ENV, hdlEnv);
    if (!SQL_SUCCEEDED(ret)) {reportError<SQLHDBC>(SQL_HANDLE_STMT, hdlStmt);}
    exit(EXIT_SUCCESS);
}

The output of running the above example is:

Connecting to database.
Connected to database.
Creating prepared statement
Executed batch.
Committing transaction
Committed transaction
Getting data from table.
id: 0
Polygon in WKB format: 01 03 00 00 00 01 00 00 00 05 00 00 00 00 00 00 00 00 00 f0 3f 00 00 00 00 00 00 f0 3f 00 00 00 00 00 00 f0 3f 00 00 00 00 00 00 00 40 00 00 00 00 00 00 00 40 00 00 00 00 00 00 00 40 00 00 00 00 00 00 00 40 00 00 00 00 00 00 f0 3f 00 00 00 00 00 00 f0 3f 00 00 00 00 00 00 f0 3f
Polygon in WKT format: POLYGON ((1 1, 1 2, 2 2, 2 1, 1 1))
Free handles.

Note

Do not use inefficient encoding formats for LONG VARBINARY and LONG VARCHAR values. The database cannot load encoded values larger than 32 MB, even if the decoded value is less than 32 MB in size. For example, the database returns an error if you attempt to load a 32 MB LONG VARBINARY value encoded in octal format, since the octal encoding quadruples the size of the value (each byte is converted into a backslash followed by three digits).

Data-Analysis: Using GEOMETRY and GEOGRAPHY data types in JDBC

Mon, 01 Jan 0001 00:00:00 +0000

GEOMETRY and GEOGRAPHY data types are backed by LONG VARBINARY native types and JDBC client applications treat them as binary data. However, these data types have a format that is unique to OpenText™ Analytics Database. To manipulate this data in your Java application, you must use the functions in the database that convert them to a recognized format.

To convert a WKT or WKB to the GEOMETRY or GEOGRAPHY format, use one of the following SQL functions:

ST_GeographyFromText—Converts a WKT to a GEOGRAPHY type.
ST_GeographyFromWKB—Converts a WKB to a GEOGRAPHY type.
ST_GeomFromText—Converts a WKT to a GEOMETRY type.
ST_GeomFromWKB—Converts a WKB to GEOMETRY type.

To convert a GEOMETRY or GEOGRAPHY object to its corresponding WKT or WKB, use one of the following SQL functions:

ST_AsText—Converts a GEOMETRY or GEOGRAPHY object to a WKT, returns a LONGVARCHAR.
ST_AsBinary—Converts a GEOMETRY or GEOGRAPHY object to a WKB, returns a LONG VARBINARY.

The following code example converts WKT and WKB data into GEOMETRY data using ST_GeomFromText and ST_GeomFromWKB and stores it in a table. Later, this example retrieves the GEOMETRY data from the table and converts it to WKT and WKB format using ST_AsText and ST_AsBinary.

import java.io.InputStream;
import java.io.Reader;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
public class GeospatialDemo
{
    public static void main(String [] args) throws Exception
    {
        Class.forName("com.vertica.jdbc.Driver");
        Connection conn =
              DriverManager.getConnection("jdbc:vertica://localhost:5433/db",
                                          "user", "password");
        conn.setAutoCommit(false);

        Statement stmt = conn.createStatement();
        stmt.execute("CREATE TABLE polygons(id INTEGER PRIMARY KEY, poly GEOMETRY)");

        int id = 0;
        int numBatches = 5;
        int rowsPerBatch = 10;

        //batch inserting WKT data
        PreparedStatement pstmt = conn.prepareStatement("INSERT INTO polygons
                                  (id, poly) VALUES(?, ST_GeomFromText(?))");
        for(int i = 0; i < numBatches; i++)
        {

            for(int j = 0; j < rowsPerBatch; j++)
            {
                //Insert your own WKT data here
                pstmt.setInt(1, id++);
                pstmt.setString(2, "polygon((1 1, 1 2, 2 2, 2 1, 1 1))");
                pstmt.addBatch();
            }
            pstmt.executeBatch();
        }

        conn.commit();
        pstmt.close();
        //batch insert WKB data
        pstmt = conn.prepareStatement("INSERT INTO polygons(id, poly)
                                      VALUES(?, ST_GeomFromWKB(?))");
        for(int i = 0; i < numBatches; i++)
        {
            for(int j = 0; j < rowsPerBatch; j++)
            {
                //Insert your own WKB data here
                byte [] wkb = getWKB();
                pstmt.setInt(1, id++);
                pstmt.setBytes(2, wkb);
                pstmt.addBatch();
            }
            pstmt.executeBatch();
        }

        conn.commit();
        pstmt.close();
        //selecting data as WKT
        ResultSet rs = stmt.executeQuery("select ST_AsText(poly) from polygons");
        while(rs.next())
        {
            String wkt = rs.getString(1);
            Reader wktReader = rs.getCharacterStream(1);
            //process the wkt as necessary
        }
        rs.close();

        //selecting data as WKB
        rs = stmt.executeQuery("select ST_AsBinary(poly) from polygons");
        while(rs.next())
        {
            byte [] wkb = rs.getBytes(1);
            InputStream wkbStream = rs.getBinaryStream(1);
            //process the wkb as necessary
        }
        rs.close();

        //binding parameters in predicates
        pstmt = conn.prepareStatement("SELECT id FROM polygons WHERE
                                      ST_Contains(ST_GeomFromText(?), poly)");
        pstmt.setString(1, "polygon((1 1, 1 2, 2 2, 2 1, 1 1))");
        rs = pstmt.executeQuery();
        while(rs.next())
        {
            int pk = rs.getInt(1);
            //process the results as necessary
        }
        rs.close();

        conn.close();
    }
}

Data-Analysis: Using GEOMETRY and GEOGRAPHY data types in ADO.NET

Mon, 01 Jan 0001 00:00:00 +0000

GEOMETRY and GEOGRAPHY data types are backed by LONG VARBINARY native types and ADO.NET client applications treat them as binary data. However, these data types have a format that is unique to OpenText™ Analytics Database. To manipulate this data in your C# application, you must use the functions in the database that convert them to a recognized format.

To convert a WKT or WKB to the GEOMETRY or GEOGRAPHY format, use one of the following SQL functions:

ST_GeographyFromText—Converts a WKT to a GEOGRAPHY type.
ST_GeographyFromWKB—Converts a WKB to a GEOGRAPHY type.
ST_GeomFromText—Converts a WKT to a GEOMETRY type.
ST_GeomFromWKB—Converts a WKB to GEOMETRY type.

To convert a GEOMETRY or GEOGRAPHY object to its corresponding WKT or WKB, use one of the following SQL functions:

ST_AsText—Converts a GEOMETRY or GEOGRAPHY object to a WKT, returns a LONGVARCHAR.
ST_AsBinary—Converts a GEOMETRY or GEOGRAPHY object to a WKB, returns a LONG VARBINARY.

The following C# code example converts WKT data into GEOMETRY data using ST_GeomFromText and stores it in a table. Later, this example retrieves the GEOMETRY data from the table and converts it to WKT and WKB format using ST_AsText and ST_AsBinary.

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 = "VerticaHost";
            builder.Database = "VMart";
            builder.User = "ExampleUser";
            builder.Password = "password123";
            VerticaConnection _conn = new
                              VerticaConnection(builder.ToString());
            _conn.Open();

            VerticaCommand command = _conn.CreateCommand();
            command.CommandText = "DROP TABLE IF EXISTS polygons";
            command.ExecuteNonQuery();
            command.CommandText =
              "CREATE TABLE polygons (id INTEGER PRIMARY KEY, poly GEOMETRY)";
            command.ExecuteNonQuery();
            // Prepare to insert a polygon using a prepared statement. Use the
            // ST_GeomFromtText SQl function to convert from WKT to GEOMETRY.
            VerticaTransaction txn = _conn.BeginTransaction();
            command.CommandText =
             "INSERT into polygons VALUES(@id, ST_GeomFromText(@polygon))";
            command.Parameters.Add(new
                           VerticaParameter("id", VerticaType.BigInt));
            command.Parameters.Add(new
                           VerticaParameter("polygon", VerticaType.VarChar));
            command.Prepare();
            // Set the values for the parameters
            command.Parameters["id"].Value = 0;
            //
            command.Parameters["polygon"].Value =
                               "polygon((1 1, 1 2, 2 2, 2 1, 1 1))";
            // Execute the query to insert the value
            command.ExecuteNonQuery();

            // Now query the table
            VerticaCommand query = _conn.CreateCommand();
            query.CommandText =
               "SELECT id, ST_AsText(poly), ST_AsBinary(poly) FROM polygons;";
            VerticaDataReader dr = query.ExecuteReader();
            while (dr.Read())
            {
                Console.WriteLine("ID: " + dr[0]);
                Console.WriteLine("Polygon WKT format data type: "
                    + dr.GetDataTypeName(1) +
                    " Value: " + dr[1]);
                // Get the WKB format of the polygon and print it out as hex.
                Console.Write("Polygon WKB format data type: "
                               + dr.GetDataTypeName(2));
                Console.WriteLine(" Value: "
                               + BitConverter.ToString((byte[])dr[2]));
            }
            _conn.Close();
        }
    }
}

The example code prints the following on the system console:

ID: 0
Polygon WKT format data type: LONG VARCHAR Value: POLYGON ((1 1, 1 2,
2 2, 2 1,1 1))
Polygon WKB format data type: LONG VARBINARY Value: 01-03-00-00-00-01
-00-00-00-05-00-00-00-00-00-00-00-00-00-F0-3F-00-00-00-00-00-00-F0-3F
-00-00-00-00-00-00-F0-3F-00-00-00-00-00-00-00-40-00-00-00-00-00-00-00
-40-00-00-00-00-00-00-00-40-00-00-00-00-00-00-00-40-00-00-00-00-00-00
-F0-3F-00-00-00-00-00-00-F0-3F-00-00-00-00-00-00-F0-3F