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 CommentsProcedural SQL (PSQL) Statements 

WHERE

The WHERE clause sets the conditions that limit the set of records for a searched delete.

In PSQL, if a named cursor is being used for deleting a set, using the WHERE CURRENT OF clause, the action is limited to the row where the cursor is currently positioned.This is a positioned delete.

Note

To be able to use the WHERE CURRENT OF clause in DSQL, the cursor name needs to be set on the statement handle before executing the statement.
Examples
DELETE FROM People
  WHERE firstname <> 'Boris' AND lastname <> 'Johnson';

DELETE FROM employee e
  WHERE NOT EXISTS(
    SELECT *
    FROM employee_project ep
     WHERE e.emp_no = ep.emp_no);

DELETE FROM Cities
  WHERE CURRENT OF Cur_Cities;  -- ESQL and PSQL only

PLAN

A PLAN clause allows the user to optimize the operation manually.

Example
DELETE FROM Submissions
  WHERE date_entered < '1-Jan-2002'
  PLAN (Submissions INDEX ix_subm_date);