[sql] ALTER TABLE 문에 ‘ON DELETE CASCADE’를 추가하는 방법

이 PL * SQL은 삭제 캐스케이드가없는 각 제한 조건을 삭제하고 삭제 캐스케이드로 다시 작성하는 스크립트를 DBMS_OUTPUT에 작성합니다.

참고 :이 스크립트의 출력 실행은 사용자의 책임입니다. 결과 스크립트를 읽고 실행하기 전에 편집하는 것이 가장 좋습니다.

DECLARE
      CURSOR consCols (theCons VARCHAR2, theOwner VARCHAR2) IS
        select * from user_cons_columns
            where constraint_name = theCons and owner = theOwner
            order by position;
      firstCol BOOLEAN := TRUE;
    begin
        -- For each constraint
        FOR cons IN (select * from user_constraints
            where delete_rule = 'NO ACTION'
            and constraint_name not like '%MODIFIED_BY_FK'  -- these constraints we do not want delete cascade
            and constraint_name not like '%CREATED_BY_FK'
            order by table_name)
        LOOP
            -- Drop the constraint
            DBMS_OUTPUT.PUT_LINE('ALTER TABLE ' || cons.OWNER || '.' || cons.TABLE_NAME || ' DROP CONSTRAINT ' || cons.CONSTRAINT_NAME || ';');
            -- Re-create the constraint
            DBMS_OUTPUT.PUT('ALTER TABLE ' || cons.OWNER || '.' || cons.TABLE_NAME || ' ADD CONSTRAINT ' || cons.CONSTRAINT_NAME
                                        || ' FOREIGN KEY (');
            firstCol := TRUE;
            -- For each referencing column
            FOR consCol IN consCols(cons.CONSTRAINT_NAME, cons.OWNER)
            LOOP
                IF(firstCol) THEN
                    firstCol := FALSE;
                ELSE
                    DBMS_OUTPUT.PUT(',');
                END IF;
                DBMS_OUTPUT.PUT(consCol.COLUMN_NAME);
            END LOOP;

            DBMS_OUTPUT.PUT(') REFERENCES ');

            firstCol := TRUE;
            -- For each referenced column
            FOR consCol IN consCols(cons.R_CONSTRAINT_NAME, cons.R_OWNER)
            LOOP
                IF(firstCol) THEN
                    DBMS_OUTPUT.PUT(consCol.OWNER);
                    DBMS_OUTPUT.PUT('.');
                    DBMS_OUTPUT.PUT(consCol.TABLE_NAME);        -- This seems a bit of a kluge.
                    DBMS_OUTPUT.PUT(' (');
                    firstCol := FALSE;
                ELSE
                    DBMS_OUTPUT.PUT(',');
                END IF;
                DBMS_OUTPUT.PUT(consCol.COLUMN_NAME);
            END LOOP;

            DBMS_OUTPUT.PUT_LINE(')  ON DELETE CASCADE  ENABLE VALIDATE;');
        END LOOP;
    end;

답변

ALTER TABLE TABLEName
drop CONSTRAINT FK_CONSTRAINTNAME;

ALTER TABLE TABLENAME
ADD CONSTRAINT FK_CONSTRAINTNAME
    FOREIGN KEY (FId)
    REFERENCES OTHERTABLE
        (Id)
    ON DELETE CASCADE ON UPDATE NO ACTION;

ALTER TABLE ChildTableName
DROP FOREIGN KEY `fk_table`;
ALTER TABLE ChildTableName
ADD CONSTRAINT `fk_t1_t2_tt`
  FOREIGN KEY (`parentTable`)
  REFERENCES parentTable (`columnName`)
  ON DELETE CASCADE
  ON UPDATE CASCADE;