## Syntax
```mermaid
%%{init: {
'theme': 'base',
'flowchart': { 'padding': '7', 'nodeSpacing': '20', 'rankSpacing': '20' },
'themeVariables': {
'fontSize': '11px',
'fontFamily': 'Arial'
}
}}%%
flowchart LR
Start((START)) --> REGEXP_INSTR[REGEXP_INSTR]:::quoted
REGEXP_INSTR --> End((END))
```
## Purpose
The `REGEXP_INSTR` SQL function determines the position of the regular expression in the given value. Returns 0 when the regular expression is not contained in the given value. The regular expression must follow the Microsoft.net regular expression language.
Parameters:
- Input: The text to get the regular expression position from.
- Pattern: Regular expression pattern.
- Start position [optional]: The start index from the input.
- Appearance [optional]: Indicating the appearance of the instr operation.
- ReturnOption [optional]: Select either the first character found or the first character after the occurrence of the pattern.
- Match_parameter [optional]: A text literal that lets you change the default matching behavior of the function.
Returns: the location of a regular expression pattern in the input.