find_in_set function
Applies to: 
Databricks SQL Databricks Runtime
Returns the position of a string within a comma-separated list of strings.
Syntax
find_in_set(searchExpr, sourceExpr)
Arguments
searchExpr: A STRING expression specifying the “word” to be searched.sourceExpr: A STRING expression with commas separating “words”.
Returns
An INTEGER.
The resulting position is 1-based and points to the first letter of the match.
If no match is found for searchExpr in sourceExpr or searchExpr contains a comma, 0 is returned.
Examples
SQL
> SELECT find_in_set('ab','abc,b,ab,c,def');
3