REGEXP_INSTR (Transact-SQL)
Applies to: 
Azure SQL Database
SQL database in Microsoft Fabric
Note
As a preview feature, the technology presented in this article is subject to Supplemental Terms of Use for Microsoft Azure Previews.
Returns the starting or ending position of the matched substring, depending on the value of the return_option argument.
REGEXP_INSTR
(
string_expression,
pattern_expression
[, start [, occurrence [, return_option [, flags [, group ] ] ] ] ]
)
Arguments
string_expression
An expression of a character string.
Can be a constant, variable, or column of character string.
Data types: char, nchar, varchar, or nvarchar.
pattern_expression
Regular expression pattern to match. Usually a text literal
Data types: char, nchar, varchar, or nvarchar. pattern_expression supports a maximum character length of 8,000 bytes.
start
Specifies the starting position for the search within the search string. Optional. Type is int or bigint.
The numbering is 1-based, meaning the first character in the expression is 1 and the value must be >= 1. If the start expression is less than 1, returns error. If the start expression is greater than the length of string_expression, the function returns 0. The default is 1.
occurrence
An expression (positive integer) that specifies which occurrence of the pattern expression within the source string to be searched or replaced. Default is 1. Searches at the first character of the string_expression. For a positive integer n, it searches for the nth occurrence beginning with the first character following the first occurrence of the pattern_expression, and so forth.
return_option
Specifies whether to return the beginning or ending position of the matched substring. Use 0 for the beginning, and 1 for the end. The default value is 0. The query returns error for any other value.
flag
One or more characters that specify the modifiers used for searching for matches. Type is varchar or char, with a maximum of 30 characters.
For example, ims. The default is c. If an empty string (' ') is provided, it will be treated as the default value ('c'). Supply c or any other character expressions. If flag contains multiple contradictory characters, then SQL Server uses the last character.
For example, if you specify ic the regex returns case-sensitive matching.
If the value contains a character other than those listed at Supported flag values, the query returns an error like the following example:
Invalid flag provided. '<invalid character>' are not valid flags. Only {c,i,s,m} flags are valid.
Supported flag values
| Flag | Description |
|---|---|
| i | Case-insensitive (default false) |
| m | Multi-line mode: ^ and $ match begin/end line in addition to begin/end text (default false) |
| s | Let . match \n (default false) |
| c | Case-insensitive (default true) |
group
Specifies which capture group (subexpression) of a pattern_expression determines the position within string_expression to return. The group is a fragment of pattern enclosed in parentheses and can be nested. The groups are numbered in the order in which their left parentheses appear in pattern. The value is an integer and must be >= 0 and must not be greater than the number of groups in the pattern_expression. The default value is 0, which indicates that the position is based on the string that matches the entire pattern_expression.
If the value is greater than the number of groups in pattern_expression, the function returns 0.
Return value
Integer.
Examples
Find the position of the first substring that contains only digits in the PRODUCT_DESCRIPTION column.
SELECT REGEXP_INSTR (PRODUCT_DESCRIPTION, '\d+') FROM PRODUCTS;
Find the position of the third occurrence of the letter a (case-insensitive) in the PRODUCT_NAME column.
SELECT REGEXP_INSTR (PRODUCT_NAME, 'a', 1, 3, 0, 'i') FROM PRODUCTS;
Find the position of the end of the first substring that starts with t and ends with e (case-sensitive) in the PRODUCT_DESCRIPTION column.
SELECT REGEXP_INSTR (PRODUCT_DESCRIPTION, 't.*?e', 1, 1, 1) FROM PRODUCTS;