This function is used to return the index of substr that appears earliest in str.

It returns NULL if either of the arguments are NULL and returns 0 if substr does not exist in str. Note that the first character in str has index 1.

Similar function: instr1. The instr1 function is used to calculate the position of the substring str2 in the string str1. The instr1 function allows you to specify the start search position and the number of matching times.

Syntax

instr(string <str>, string <substr>)

Parameters

**Table 1** Parameters
Parameter	Mandatory	Type	Description
str	Yes	STRING	Target string to be searched for If the value is of the BIGINT, DOUBLE, DECIMAL, or DATETIME type, the value is implicitly converted to the STRING type for calculation. For other types of values, an error is reported.
substr	Yes	STRING	Substring to be matched If the value is of the BIGINT, DOUBLE, DECIMAL, or DATETIME type, the value is implicitly converted to the STRING type for calculation. For other types of values, an error is reported.

Return Values

The return value is of the BIGINT type.

If str2 is not found in str1, 0 is returned.
If str2 is an empty string, the matching is always successful. For example, select instr('abc',''); returns 1.
If the value of str1 or str2 is NULL, NULL is returned.

Example Code

Returns the position of character b in string abc. An example command is as follows:
The value 2 is returned.
```
select instr('abc', 'b');
```
The value of any input parameter is NULL. An example command is as follows:
The value NULL is returned.
```
select instr('abc', null)
```