Delete a child and a parent row with one SQL script

Question

Instead of deleting the child row and then writing another sql statement to delete the parent row I wanted to use one statement which will do both. FYI: we use Oracle databa

Answer 1

In case it helps anyone else, I just wrote a PLSQL script to do this for all foreign key constraints in a table with some help from this Stackoverflow question. Hope it helps.

DECLARE
  CURSOR constraint_cursor IS SELECT *
                              FROM (SELECT a.table_name,
                                           a.constraint_name,
                                           a.column_name,
                                           c_pk.table_name r_table_name,
                                           b.column_name   r_column_name
                                    FROM user_cons_columns a
                                           JOIN user_constraints c ON a.owner = c.owner
                                                                        AND a.constraint_name = c.constraint_name
                                           JOIN user_constraints c_pk ON c.r_owner = c_pk.owner
                                                                           AND
                                                                         c.r_constraint_name = c_pk.constraint_name
                                           JOIN user_cons_columns b ON C_PK.owner = b.owner
                                                                         AND
                                                                       C_PK.CONSTRAINT_NAME = b.constraint_name AND
                                                                       b.POSITION = a.POSITION
                                    WHERE c.constraint_type = 'R'
                                      and c_pk.owner = 'YOUR SCHEMA HERE') tbl;
  sql_statement VARCHAR2(2048) := NULL;
  tab_row       constraint_cursor%rowtype;
BEGIN
  OPEN constraint_cursor;
  FOR i in 1..80 LOOP
    FETCH constraint_cursor into tab_row;
    EXECUTE IMMEDIATE 'ALTER table ' || tab_row.table_name || ' drop constraint ' || tab_row.constraint_name;
    EXECUTE IMMEDIATE 'ALTER table ' || tab_row.table_name || ' add constraint ' || tab_row.constraint_name || ' FOREIGN KEY (' ||
    tab_row.column_name || ') references ' || tab_row.r_table_name || '(' || tab_row.r_column_name || ') ON DELETE CASCADE ';
  end loop;
  close constraint_cursor;
end;