Package org.datanucleus.store.rdbms.sql

Series of classes used to generate SQL statements.

See: Description

Interface Summary

Interface	Description
SQLTableNamer	Interface to be implemented by a class providing naming for SQL tables.
StatementGenerator	Generator of SQLStatements.

Class Summary

Class	Description
AbstractStatementGenerator	Abstract generator of SQLStatements.
DiscriminatorStatementGenerator	Class to generate an SQLStatement for iterating through instances of a particular type (and optionally subclasses).
SQLColumn	Representation of a column reference in an SQL statement.
SQLJoin	Representation of a join in an SQL statement.
SQLStatement	Class providing an API for generating SQL statements.
SQLStatementHelper	Series of convenience methods to help the process of generating SQLStatements.
SQLStatementParameter	Representation of an SQLStatement parameter.
SQLTable	Representation of a table reference in an SQL statement.
SQLTableAlphaNamer	SQLTable namer that generates names like A0, B1, C0, ...
SQLTableGroup	Group of tables in an SQL statement.
SQLTableNameNamer	SQLTable namer that uses the table name as the "alias".
SQLTableTNamer	SQLTable namer that generates names like T0, T1, T2, etc.
SQLText	Representation of a snippet of an SQL statement.
UnionStatementGenerator	Class to generate an SQLStatement for iterating through instances of a particular type (and optionally subclasses).

Enum Summary

Enum	Description
SQLJoin.JoinType

Package org.datanucleus.store.rdbms.sql Description

Series of classes used to generate SQL statements. Based around the notion that an SQL statement (SQLStatement) has a series of tables (SQLTable) involved, with a series of joins (SQLJoin), subject to a series of conditions, based on expressions (see org.datanucleus.store.rdbms.sql.expression. The tables involved in the statement can be grouped for convenience to represent objects and relations between objects (like in JDOQL/JPQL). This package has now replaced FetchStatement, and will also replace QueryStatement, StatementText and all code under org.datanucleus.store.mapped.expression.

Provides helpers to generate the SQLStatement. These include

• DiscriminatorStatementGenerator that selects a candidate table and uses the discriminator column of that table (or of its supertable) to identify the returned object
• UnionStatementGenerator that does a UNION of all possible candidates selecting a column "NUCLEUS_TYPE" to identify the object type of the row.
• Numerous methods of SQLStatementHelper to assist in joining between tables of an inheritance tree, and across relations.

Allows control over how tables in the SQL statement are aliased. This uses a plugin-point org.datanucleus.store.rdbms.sql_tablenamer and DataNucleus provides the following options

• alpha-scheme where tables are named using a letter to symbolise their "table-group", followed by a number for the number within that group. So you get names like A0, A1, A2, A3, B0, B1, C0 etc
• t-scheme where tables are named T0, T1, T2, T3, etc