In SQL, the DROP AGGREGATE statement is used to remove an aggregate function that has been defined in the database. Aggregate functions are typically user-defined functions that operate on a set of values and return a single value. This is common in databases like PostgreSQL.
Here’s the general syntax to use the DROP AGGREGATE statement:
DROP AGGREGATE [ IF EXISTS ] schema_name.agg_function_name (data_type [, ...] )
- IF EXISTS is optional and prevents an error from being thrown if the aggregate function does not exist.
- schema_name is the name of the schema where the aggregate function is defined.
- agg_function_name is the name of the aggregate function you want to drop.
- (data_type [, ...]) specifies the data types of the arguments the aggregate function accepts. This is necessary to uniquely identify the aggregate if there are multiple overloaded versions.
Example
Suppose you have defined an aggregate function called my_sum that operates on integer data types. You can remove it using the following statement:
DROP AGGREGATE IF EXISTS my_schema.my_sum(integer);
This statement will drop the my_sum aggregate function from the my_schema schema, but only if it exists, avoiding an error if it doesn’t.
Notes
- Before dropping an aggregate function, ensure it is not being used by any views, indexes, or other database objects to avoid breaking those dependencies.
- The availability and behavior of the DROP AGGREGATE statement can vary between different database management systems, so always check your specific DBMS documentation for exact usage and syntax.