| Function Type | Definition |
|---|---|
| Scalar | The arguments are individual scalar values of either the same or mixed type that can have different meanings. The result is a single value or null. Scalar functions can be used in any SQL statement where an expression can be used. |
| Aggregate | The argument is a group of rows. The result is a single value or null. Typically aggregate functions are used in the expression list of a SELECT statement and in the summary list of a WITH clause. |
| Table | The arguments are individual scalar values of either same or mixed type that can have different meanings. The result is a table. Table functions are a form of user-defined functions can be used only within the FROM clause of a SELECT statement. |
| Ordered Analytical | The arguments are any normal SQL expression. The result is handled as an SQL expression. The result can be a result column or part of a more complex arithmetic expression. Ordered analytical functions are used in operations that require an ordered set of results rows or that depend on values in a previous row. |