Rules for Using Correlated Subqueries in a DELETE Statement
The following rules apply to correlated subqueries used in a DELETE statement:
A DELETE statement requires that if joined tables are specified, all tables referenced
in the DELETE statement must be specified in the FROM clause, including the deleted
table.
A table_name must be added to specify the deleted table name in this case.
All correlation names must be defined in the FROM clause.
Correlation names are also referred to as range variables and aliases.
If a correlation name is defined for the deleted table name in the FROM clause, then
that correlation name, not the original table name, must be used as the table_name that follows the DELETE keyword.
If an inner query column specification references an outer FROM clause table, then
the column reference must be fully qualified.
The table_name preceding the FROM clause is optional if no joined tables are specified for deletion.
Also see “Correlated Subqueries” on page 116.