INDEX(a,b,p,s) is an arithmetic function that determines the position of the substring specified in b within the character string a. a and b are string specifications. Only expressions that have an alphanumeric value are permitted as string specifications.
The parameter p (an expression) is optional. If p is specified (p>=1), it defines the start position for the search for the substring b. If p is not specified, the search is started at position 1.
The parameter s (an expression) is optional. If s is specified, it determines the number of searches for the substring b. If s is not specified, the search is carried out for the first occurrence.
a, b, p, s |
Result of the INDEX(a,b,p,s) function |
---|---|
a, b are character strings and b is not less than s times the substring of a |
0 |
a is a character string and b is an empty character string |
p |
a, b, p or s is the NULL value |
NULL value |
p or s is a special NULL value |
Error Messages |
SQL Tutorial, Information About Character Strings