The jOOQ User Manual SQL building QueryParts Declaration vs reference

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Declaration vs reference

Applies to ✅ Open Source Edition   ✅ Express Edition   ✅ Professional Edition   ✅ Enterprise Edition

A few types of org.jooq.QueryPart render different SQL depending on the context in which they are being rendered. The context is whether:

• The object is being declared
• The object is being referenced

A simple example is the aliasing of tables and columns. For example:

// Alias the table BOOK
Book b = BOOK.as("B");

// Use the alias as a reference
create.select(b.ID)

// Use the alias as a declaration
      .from(b)
      .fetch();

In the above example, when referencing the table alias, jOOQ renders the alias only, i.e. B. When declaring the table alias, jOOQ renders both the original table and its alias, i.e. BOOK as B.

While it may appear useful to occasionally enter in a third rendering mode, which renders the original table BOOK only, ignoring the alias, this isn't what is happening. If you want to access the original table (or column) reference, just keep a reference to that in your code, instead.

Types that expose this behaviour

The following types of org.jooq.QueryPart expose this kind of context sensitive rendering behaviour:

• org.jooq.Table: Table expressions can be aliased tables which can be declared in the FROM clause, or similar clauses of other statements.
• org.jooq.Field: Field expressions can be aliased columns which can be declared in the SELECT clause, or the RETURNING clauses of various statements.
• org.jooq.CommonTableExpression: Common table expressions can be declared in the WITH clause of various statements.
• org.jooq.WindowDefinition: Window definitions can be declared in the WINDOW clause of the SELECT statement.
• org.jooq.Parameter: Routine parameters can be declared in the CREATE FUNCTION or CREATE PROCEDURE statements.

The jOOQ User Manual SQL building QueryParts Declaration vs reference

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