Home
SQL programmingYou can use the HCL OneDB™ implementation of the SQL language to develop applications for HCL OneDB™ database servers.
Guide to SQL: SyntaxThe HCL OneDB™ Guide to SQL: Syntax describes the syntax of the statements, data types, expressions, operators, and built-in functions of the HCL OneDB™ dialect of the SQL language.
SQL statementsThis chapter describes the syntax and semantics of SQL statements that are recognized by HCL OneDB™.
CREATE AGGREGATE statementUse the CREATE AGGREGATE statement to create a new aggregate function and register it in the sysaggregates system catalog table.
Extending the Functionality of Aggregates

Extending the Functionality of Aggregates

HCL OneDB™ provides two ways to extend the functionality of aggregates. Use the CREATE AGGREGATE statement only for the second of the two cases.

Extensions of built-in aggregates
A built-in aggregate is an aggregate that the database server provides, such as COUNT, SUM, or AVG. These only support built-in data types. To extend a built-in aggregate so that it supports a user-defined data type (UDT), you must create user-defined routines that overload the binary operators for that aggregate. For further information on extending built-in aggregates, see the HCL OneDB User-Defined Routines and Data Types Developer's Guide.
Creation of user-defined aggregates
A user-defined aggregate is an aggregate that you define to perform an aggregate computation that the database server does not provide. You can use user-defined aggregates with built-in data types, extended data types, or both. To create a user-defined aggregate, use the CREATE AGGREGATE statement. In this statement, you name the new aggregate and specify the support functions that compute the aggregate result. These support functions perform initialization, sequential aggregation, combination of results, and type conversion.

Have feedback?
Google Analytics is used to store comments and ratings. To provide a comment or rating for a topic, click Accept All Cookies or Allow All in Cookie Preferences in the footer of this page.