16.20 - REGEXP_SUBSTR - Teradata Vantage NewSQL Engine

Teradata Vantageā„¢ SQL Functions, Expressions, and Predicates

prodname
Teradata Database
Teradata Vantage NewSQL Engine
vrm_release
16.20
category
Programming Reference
featnum
B035-1145-162K

Purpose

Extracts a substring from source_string that matches a regular expression specified by regexp_string.

REGEXP_SUBSTR supports 2, 3, 4, or 5 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.
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 number of the occurrence to be returned (default is 1). For example, if occurrence_arg is 2, the function matches the first occurrence in source_string and starts searching from the character following the first occurrence in source_string for the second occurrence in source_string.
If occurrence_arg is greater than the number of matches found, NULL is returned.
If occurrence_arg is NULL, a NULL result is returned. If occurrence_arg is omitted, the default value (1) is used.
match_arg

A character argument.

Valid values are:
  • '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' = 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.
  • 'x' = ignore whitespace.
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.