sql select and remove code example

Example 1: sql delete where in select

DELETE FROM tableA
WHERE ROWID IN 
  ( SELECT q.ROWID
    FROM tableA q
      INNER JOIN tableB u on (u.qlabel = q.entityrole AND u.fieldnum = q.fieldnum) 
    WHERE (LENGTH(q.memotext) NOT IN (8,9,10) OR q.memotext NOT LIKE '%/%/%')
      AND (u.FldFormat = 'Date'));

Example 2: delete and drop in sql

DELETE -
-DML COMMAND
-Delete Rows from the table one by one
-We can use where clause with Delete to delete single row
-Delete is slower than truncate
-ROLLBACK is possible with DELETE

DROP-
-DDL COMMAND
-Delete the entire structure or schema
-We can't use where clause with drop
-Drop is slower than DELETE & TRUNCATE
-ROLLBACK IS NOT POSSIBLE WITH DROP

TRUNCATE-
-DDL COMMAND
-Truncate deletes rows at a one goal
-We can't use where clause with Truncate
-Truncate faster than both DELETE & DROP
-Rollback is not possible with Truncate