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Updated on 2023-10-25 GMT+08:00
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regexp_substr

This function is used to return the substring that matches a specified pattern for the occurrence time, starting from start_position in the string source.

Syntax

regexp_substr(string <source>, string <pattern>[, bigint <start_position>[, bigint <occurrence>]])

Parameters

Table 1 Parameters

Parameter

Mandatory

Type

Description

source

Yes

STRING

String to be searched for

pattern

Yes

STRING

Constant or regular expression of the STRING type. Pattern to be matched.

start_position

No

BIGINT

Start position. The value must be greater than 0. If this parameter is not specified, the default value 1 is used, indicating that the matching starts from the first character of source.

occurrence

No

BIGINT

The value is a constant of the BIGINT type, which must be greater than 0. If it is not specified, the default value 1 is used, indicating that the substring matched for the first time is returned.

Return Values

The return value is of the STRING type.

  • If the value of pattern is an empty string, an error is reported.
  • If no match is found, NULL is returned.
  • If the value of start_position or occurrence is not of the BIGINT type or is less than or equal to 0, an error is reported.
  • If the value of source, pattern, start_position, occurrence, or return_option is NULL, NULL is returned.

Example Code

The value a is returned.

select regexp_substr('a1b2c3', '[a-z]');

The value b is returned.

select regexp_substr('a1b2c3', '[a-z]', 2, 1);

The value c is returned.

select regexp_substr('a1b2c3', '[a-z]', 2, 2);

The value NULL is returned.

select regexp_substr('a1b2c3', null);
Parent topic: String Functions