Basic Language Elements › Column Names › Correlation Names

Correlation Names

A correlation-name can be defined in any FROM clause.

For example, the clause

          .
          .
 FROM X.MYTABLE Z, Y.MYTABLE
          .
          .

Establishes Z as a correlation-name for X.MYTABLE. Z can be used anywhere in the SELECT statement to designate that particular table.

A correlation-name is associated with a table or view only within the context in which it is defined. The same correlation-name can be defined for different purposes in different statements, or in different clauses of the same statement.

As a qualifier, a correlation-name can be used:

• To avoid ambiguity
• To establish a correlated reference
• As a shorter name for a table or view

In the previous example, Z could be used to avoid having to enter X.MYTABLE more than once.