## INDEX(a,b,p,s)

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.

| Result of the INDEX(a,b,p,s) function
a, b character strings and b not less than s times substring of a | 0
a character string and b empty character string | p
a, b, p or s is the NULL value | NULL Value
p or s is special NULL value | Error message

### Examples

SQL Tutorial, Information About Character Strings