16.20 - REGEXP_REPLACE - Advanced SQL Engine - Teradata Database

Purpose

Replaces portions of source_string that match regexp_string with the replace_string.

REGEXP_REPLACE supports 2, 3, 4, 5, or 6 parameters.

Syntax

TD_SYSFNLIB.

Name of the database where the function is located.

source_string

A character argument.

If source_string is NULL, NULL is returned.

regexp_string

A character argument.

If regexp_string is NULL, NULL is returned.

replace_string

A character argument.

If a replace_string is not specified, is NULL or is an empty string, the matches are removed from the result.

The maximum backreference number in a replace_string is 9 (for example, \9). Any backreference in the replace_string that is higher than 9 is considered a backreference.

position_arg

A numeric argument.

position_arg specifies the position in source_string from which to start searching (default is 1).

If position_arg is greater than the input string length, NULL is returned.

If position_arg is NULL, the value NULL is used. If position_arg is not specified, the default (1) is used.

occurrence_arg

A numeric argument.

Specifies the occurrence to replace the match with replace_string.

• If a value of 0 is specified, all occurrences are replaced.
• If the value is greater than 1, the search begins for the second occurrence beginning with the first character following the first occurrence of the regexp_string, and so on.

If occurrence_arg is greater than the number of matches found, nothing is replaced and source_string is returned.

If occurrence_arg is NULL, a NULL result is returned. If occurrence_arg is omitted, 0 is the default value.

match_arg

A character argument.

The argument can contain more than one character. If a character in the argument is not valid, then that character is ignored.

If match_arg is not specified, is NULL, or is empty:

• The match is case-sensitive.
• A period does not match the newline character.
• source_string is treated as a single line.

• 'i' = case-insensitive matching.
• 'c' = case-sensitive matching.
• 'n' = the period character (match any character) can match the newline character.
• 'm' = source_string is treated as multiple lines instead of as a single line. With this option, the '^' and '$' characters apply to each line in source_string instead of the entire source_string.
• 'l' = For a CLOB data type, if source_string exceeds the current maximum allowed source_string size (currently 16 MB), a NULL is returned instead of an error. This is useful for long-running queries where you do not want long strings causing an error that would make the query fail. You can only specify this option for a CLOB data type.
• 'x' = ignore whitespace.

REGEXP_REPLACE supports 2, 3, 4, 5, or 6 parameters.

Limitation: NULL inside Input Strings

sel TD_SYSFNLIB.RegExp_Replace ('a'||chr(0)||'bc', '[b]', 'X', 1, 0) AS 
regex_rep_input_string;