Vertica Documentation – String literals

Sql-Reference: Character string literals

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

Character string literals are a sequence of characters from a predefined character set, enclosed by single quotes.

Syntax

'character-seq'

Parameters

character-seq: Arbitrary sequence of characters

Embedded single quotes

If a character string literal includes a single quote, it must be doubled. For example:

=> SELECT 'Chester''s gorilla';
  ?column?
-------------------
Chester's gorilla
(1 row)

Standard-conforming strings and escape characters

Vertica uses standard-conforming strings as specified in the SQL standard, so backslashes are treated as string literals and not escape characters.

Note

Earlier versions of Vertica did not use standard conforming strings, and backslashes were always considered escape sequences. To revert to this older behavior, set the configuration parameter StandardConformingStrings to 0. You can also use the EscapeStringWarning parameter to locate back slashes which have been incorporated into string literals, in order to remove them.

Examples

=> SELECT 'This is a string';
  ?column?
------------------
 This is a string
(1 row)
=> SELECT 'This \is a string';
   WARNING:  nonstandard use of escape in a string literal at character 8
   HINT:  Use the escape string syntax for escapes, e.g., E'\r\n'.
     ?column?
------------------
 This is a string
(1 row)
vmartdb=> SELECT E'This \is a string';
     ?column?
------------------
 This is a string
=> SELECT E'This is a \n new line';
       ?column?
----------------------
 This is a
 new line
(1 row)
=> SELECT 'String''s characters';
      ?column?
--------------------
 String's characters
(1 row)

Sql-Reference: Dollar-quoted string literals

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

Dollar-quoted string literals are rarely used, but are provided here for your convenience.

The standard syntax for specifying string literals can be difficult to understand. To allow more readable queries in such situations, Vertica SQL provides dollar quoting. Dollar quoting is not part of the SQL standard, but it is often a more convenient way to write complicated string literals than the standard-compliant single quote syntax.

Syntax

$$characters$$

Parameters

characters: Arbitrary sequence of characters bounded by paired dollar signs ($$)

Dollar-quoted string content is treated as a literal. Single quote, backslash, and dollar sign characters have no special meaning within a dollar-quoted string.

Notes

A dollar-quoted string that follows a keyword or identifier must be separated from the preceding word by whitespace; otherwise, the dollar-quoting delimiter is taken as part of the preceding identifier.

Examples

=> SELECT $$Fred's\n car$$;
     ?column?
-------------------
 Fred's\n car
(1 row)

=> SELECT 'SELECT 'fact';';
ERROR:  syntax error at or near "';'" at character 21
LINE 1: SELECT 'SELECT 'fact';';

=> SELECT 'SELECT $$fact';$$;
   ?column?
---------------
 SELECT $$fact
(1 row)

=> SELECT 'SELECT ''fact'';';
    ?column?
----------------
 SELECT 'fact';
(1 row)

Sql-Reference: Unicode string literals

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

Syntax

U&'characters' [ UESCAPE '<Unicode escape character>' ]

Parameters

characters: Arbitrary sequence of UTF-8 characters bounded by single quotes (')
Unicode escape character: A single character from the source language character set other than a hexit, plus sign (+), quote ('), double quote (''), or white space

Using standard conforming strings

With StandardConformingStrings enabled, Vertica supports SQL standard Unicode character string literals (the character set is UTF-8 only).

Before you enter a Unicode character string literal, enable standard conforming strings in one of the following ways.

To enable for all sessions, update the configuration parameter StandardConformingStrings.
To treat backslashes as escape characters for the current session, use the SET STANDARD_CONFORMING_STRINGS statement.

Examples

To enter a Unicode character in hexadecimal, such as the Russian phrase for "thank you, use the following syntax:

=> SET STANDARD_CONFORMING_STRINGS TO ON;
=> SELECT U&'\0441\043F\0430\0441\0438\0431\043E' as 'thank you';
 thank you
-----------
 спасибо
(1 row)

To enter the German word mude (where u is really u-umlaut) in hexadecimal:

=> SELECT U&'m\00fcde';
?column?
----------
müde
(1 row)
=> SELECT 'ü';
?column?
----------
ü
(1 row)

To enter the LINEAR B IDEOGRAM B240 WHEELED CHARIOT in hexadecimal:

=> SELECT E'\xF0\x90\x83\x8C';
?column?
----------
(wheeled chariot character)
(1 row)

Note

Not all fonts support the wheeled chariot character.

Sql-Reference: VARBINARY string literals

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

VARBINARY string literals allow you to specify hexadecimal or binary digits in a string literal.

Syntax

X''
B''

Parameters

X or x: Specifies hexadecimal digits. The <hexadecimal digits> string must be enclosed in single quotes (').
B or b: Specifies binary digits. The <binary digits> string must be enclosed in single quotes (').

Examples

=> SELECT X'abcd';
 ?column?
----------
 \253\315
(1 row)

=> SELECT B'101100';
 ?column?
----------
 ,
(1 row)

Sql-Reference: Extended string literals

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

Syntax

E'characters'

Parameters

characters: Arbitrary sequence of characters bounded by single quotes (') You can use C-style backslash sequence in extended string literals, which are an extension to the SQL standard. You specify an extended string literal by writing the letter E as a prefix (before the opening single quote); for example:

E'extended character string\n'

Within an extended string, the backslash character (\) starts a C-style backslash sequence, in which the combination of backslash and following character or numbers represent a special byte value, as shown in the following list. Any other character following a backslash is taken literally; for example, to include a backslash character, write two backslashes (\\).

\\ is a backslash
\b is a backspace
\f is a form feed
\n is a newline
\r is a carriage return
\t is a tab
\x##,where ## is a 1 or 2-digit hexadecimal number; for example \x07 is a tab
\###, where ### is a 1, 2, or 3-digit octal number representing a byte with the corresponding code.

When an extended string literal is concatenated across lines, write only E before the first opening quote:

=> SELECT E'first part o'
    'f a long line';
         ?column?
---------------------------
 first part of a long line
(1 row)

Two adjacent single quotes are used as one single quote:

=> SELECT 'Aren''t string literals fun?';
          ?column?
-----------------------------
 Aren't string literals fun?
(1 row)

Standard conforming strings and escape characters

When interpreting commands, such as those entered in vsql or in queries passed via JDBC or ODBC, Vertica uses standard conforming strings as specified in the SQL standard. In standard conforming strings, backslashes are treated as string literals (ordinary characters), not escape characters.

Note

Text read in from files or streams (such as the data inserted using the COPY statement) are not treated as literal strings. The COPY command defines its own escape characters for the data it reads. See the COPY statement documentation for details.

The following options are available, but Vertica recommends that you migrate your application to use standard conforming strings at your earliest convenience, after warnings have been addressed.

To treat back slashes as escape characters, set configuration parameter StandardConformingStrings to 0.
To enable standard conforming strings permanently, set the StandardConformingStrings parameter to '1', as described below.
To enable standard conforming strings per session, use SET STANDARD_CONFORMING_STRING TO ON, which treats backslashes as escape characters for the current session only.

Identifying strings that are not standard conforming

The following procedure can be used to identify nonstandard conforming strings in your application so that you can convert them into standard conforming strings:

Be sure the StandardConformingStrings parameter is off, as described in Internationalization parameters.
```
=> ALTER DATABASE DEFAULT SET StandardConformingStrings = 0;
```
Note
Vertica recommends that you migrate your application to use standard conforming strings .
If necessary, turn on the EscapeStringWarning parameter.
```
=> ALTER DATABASE DEFAULT SET EscapeStringWarning = 1;
```
Vertica now returns a warning each time it encounters an escape string within a string literal. For example, Vertica interprets the \n in the following example as a new line:
```
=> SELECT 'a\nb';
   WARNING:  nonstandard use of escape in a string literal at character 8
   HINT:  Use the escape string syntax for escapes, e.g., E'\r\n'.
 ?column?
----------
 a
b
(1 row)
```
When StandardConformingStrings is ON, the string is interpreted as four characters: a \ n b.

Modify each string that Vertica flags by extending it as in the following example:
```
E'a\nb'
```
Or if the string has quoted single quotes, double them; for example, 'one'' double'.
Turn on the StandardConformingStrings parameter for all sessions:
```
=> ALTER DATABASE DEFAULT SET StandardConformingStrings = 1;
```

Doubled single quotes

This section discusses vsql inputs that are not passed on to the server. Vertica recognizes two consecutive single quotes within a string literal as one single quote character. For example, the following inputs, 'You''re here!' ignored the second consecutive quote and returns the following:

=> SELECT 'You''re here!';
   ?column?
--------------
 You're here!at
(1 row)

This is the SQL standard representation and is preferred over the form, 'You\'re here!', because backslashes are not parsed as before. You need to escape the backslash:

=> SELECT (E'You\'re here!');
   ?column?
--------------
 You're here!
(1 row)

This behavior change introduces a potential incompatibility in the use of the vsql meta-command \set, which automatically concatenates its arguments. For example:

\set file  '\''  'pwd'  '/file.txt'  '\''\echo :file

vsql takes the four arguments and outputs the following:

'/home/vertica/file.txt'

Vertica parses the adjacent single quotes as follows:

\set file  '\'''pwd''/file.txt''\''\echo :file
'/home/vertica/file.txt''

Note the extra single quote at the end. This is due to the pair of adjacent single quotes together with the backslash-quoted single quote.

The extra quote can be resolved either as in the first example above, or by combining the literals as follows:

\set file '\''`pwd`'/file.txt'''\echo :file
'/home/vertica/file.txt'

In either case the backslash-quoted single quotes should be changed to doubled single quotes as follows:

\set file '''' `pwd` '/file.txt'''

Additional examples

=> SELECT 'This \is a string';
     ?column?
------------------
 This \is a string
(1 row)

=> SELECT E'This \is a string';
     ?column?
------------------
 This is a string

=> SELECT E'This is a \n new line';
       ?column?
----------------------
 This is a
 new line
(1 row)

=> SELECT 'String''s characters';
      ?column?
--------------------
 String's characters
(1 row)

Vertica Documentation – String literals

Sql-Reference: Character string literals

Syntax

Parameters

Embedded single quotes

Standard-conforming strings and escape characters

Note

Examples

See also

Sql-Reference: Dollar-quoted string literals

Syntax

Parameters

Notes

Examples

Sql-Reference: Unicode string literals

Syntax

Parameters

Using standard conforming strings

Examples

Note

See also

Sql-Reference: VARBINARY string literals

Syntax

Parameters

Examples

Sql-Reference: Extended string literals

Syntax

Parameters

Standard conforming strings and escape characters

Note

Identifying strings that are not standard conforming

Note

Doubled single quotes

Additional examples