substring function
Applies to: 
Databricks SQL Databricks Runtime
Returns the substring of expr that starts at pos and is of length len. This function is a synonym for substr function.
Syntax
substring(expr, pos [, len])
substring(expr FROM pos [FOR len] ] )
Arguments
expr: AnBINARYorSTRINGexpression.pos: An integral numeric expression specifying the starting position.len: An optional integral numeric expression.
Returns
A STRING.
pos is 1 based. If pos is negative the start is determined by counting characters (or bytes for BINARY) from the end.
If len is less than 1 the result is empty.
If len is omitted the function returns on characters or bytes starting with pos.
Examples
SQL
> SELECT substring('Spark SQL', 5);
k SQL
> SELECT substring('Spark SQL', -3);
SQL
> SELECT substring('Spark SQL', 5, 1);
k
> SELECT substring('Spark SQL' FROM 5);
k SQL
> SELECT substring('Spark SQL' FROM -3);
SQL
> SELECT substring('Spark SQL' FROM 5 FOR 1);
k
> SELECT substring('Spark SQL' FROM -10 FOR 5);
Spar