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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.
Projection ClauseThe Projection clause (sometimes called the Select clause) specifies a list of database objects or expressions to retrieve, and can set restrictions on qualifying rows. (The select list is sometimes also called the projection list.)
Data Types in Distributed Queries

Data Types in Distributed Queries

Queries whose only data sources are tables and views in the local database to which the session is connected can return values from columns or expressions of any built-in or user-defined data type that is registered in the local database. Queries that reference tables or views in other databases are called distributed queries, and the data types that they can access are a subset of the data types that HCL OneDB™ supports in local queries.

Among distributed queries, the restrictions on data types depend on the number of participating database servers.

If all the databases that the query accesses are databases of the same HCL OneDB instance, the query is called a cross-database distributed query.
If the query accesses databases of multiple HCL OneDB instances, the query is called a cross-server distributed query.

In both types of distributed queries, all participating databases must have the same ANSI/ISO-compliance status. A cross-server distributed query can use both the SKIP and FIRST options if all participating servers support the SKIP option; otherwise the query fails with an error. More generally, all cross-server operations require that the participating database server instances support the SQL syntax that specifies the operation.

For additional information about distributed queries, see the HCL OneDB Database Design and Implementation Guide.

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