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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™.
SELECT statementUse the SELECT statement to retrieve values from a database or from an SPL or collection variable. A SELECT operation is called a query.
FROM ClauseThe FROM clause of the SELECT statement lists table objects from which to retrieve data.
Restrictions on External Tables in Joins and Subqueries

Restrictions on External Tables in Joins and Subqueries

When you use external tables in joins or subqueries, the following restrictions apply:

No more than one external table is valid in a query.
The external table cannot be the outer table in an outer join.
For subqueries that cannot be converted to joins, you can use an external table in the main query, but not in the subquery.
You cannot do a self-join on an external table.

For more information on subqueries, see your HCL OneDB™ Performance Guide.