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Updated on 2023-10-25 GMT+08:00
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instr1

This function is used to return the position of substring str2 in string str1.

Similar function: instr. The instr function is used to return the index of substr that appears earliest in str. However, instr does not support specifying the start search position and matching times.

Syntax

instr1(string <str1>, string <str2>[, bigint <start_position>[, bigint <nth_appearance>]])

Parameters

Table 1 Parameters

Parameter

Mandatory

Type

Description

str1

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.

str2

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.

start_position

No

BIGINT

Sequence number of the character in str1 the search starts from. The default start position is position 1 (position of the first character).

If this parameter is set to a negative number, the search starts from the end to the beginning of the string, and the last character is -1.

nth_appearance

No

BIGINT

Position of str2 that is matched for the nth_appearance time in str1.

If the value is of another type or is less than or equal to 0, 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.
  • If the value of str1, str2, start_position, or nth_appearance is NULL, NULL is returned.

Example Code

The value 10 is returned.

select instr1('Tech on the net', 'h', 5, 1);

The value 2 is returned.

select instr1('abc', 'b');

The value NULL is returned.

select instr('abc', null);
Parent topic: String Functions