This function returns the position in string at which search_string appears. If this is not contained, the value 0 is returned.
The optional parameter position defines the search direction and at which position the search shall start:
If position is positive, the string is searched from the beginning to the end, starting at the character position counted from the beginning (the first character has position 1).
If position is negative, the string is searched from the end to the beginning, starting at character position counted from the end (the last character has position -1). The return value is counted from the beginning to the end, so the function will never return a negative value.
Example: INSTR(string,'abc',-3) will search backwards starting from the third last character in the string.
The optional positive number occurrence defines which occurrence shall be searched for.
INSTR(string,search_string) is similar to INSTR(string,search_string,1,1).
SELECT INSTR('abcabcabc','cab') INSTR1,
INSTR('user1,user2,user3,user4,user5','user', -1, 2) INSTR2;