Question

父表是

CREATE TABLE BHEAD (
ID INTEGER primary key asc, 
DESCR TEXT, 
LINECTR INT, 
UNITCTR INT)

子表是

CREATE TABLE BDET (
ID INTEGER primary key asc,
BID INTEGER,
BCODE TEXT,
QTY INTEGER,
FOREIGN KEY (BID) REFERENCES BHEAD(ID) ON DELETE CASCADE
)

我也执行sql PRAGMA foreign_keys = ON; 但它不起作用;当我从BHEAD删除一行时，其BDET中的关联行不会消失...

为什么会这样？

Answer 1

您使用的是什么版本的SQLite？

请参阅：Foreign Keys。

为了在SQLite中使用外键约束，必须在既未定义SQLITE_OMIT_FOREIGN_KEY或SQLITE_OMIT_TRIGGER的情况下编译库。

Answer 2

但是，您也可以在删除级联上实施以删除所有子项父行被删除时的行。

-- Create the test tables using ON DELETE CASCADE
DROP TABLE t3 PURGE;
--DROP TABLE t2 PURGE;
--DROP TABLE t1 PURGE;

CREATE TABLE t1 (
  id           NUMBER,
  description  VARCHAR2(50),
  CONSTRAINT t1_pk PRIMARY KEY (id)
);

CREATE TABLE t2 (
  id             NUMBER,
  t1_id          NUMBER,
  description    VARCHAR2(50),
  CONSTRAINT t2_pk PRIMARY KEY (id),
  CONSTRAINT t2_t1_fk FOREIGN KEY (t1_id) REFERENCES t1 (id) ON DELETE CASCADE
);

CREATE TABLE t3 (
  id             NUMBER,
  t2_id          NUMBER,
  description    VARCHAR2(50),
  CONSTRAINT t3_pk PRIMARY KEY (id),
  CONSTRAINT t3_t2_fk FOREIGN KEY (t2_id) REFERENCES t2 (id)
);


INSERT INTO t1 VALUES (1, 't1 ONE');

INSERT INTO t2 VALUES (1, 1, 't2 ONE');
INSERT INTO t2 VALUES (2, NULL, 't2 TWO');

INSERT INTO t3 VALUES (1, 1, 't3 ONE');
INSERT INTO t3 VALUES (2, NULL, 't3 TWO');
COMMIT;


SELECT (SELECT COUNT(*) FROM t1) AS t1_count,
       (SELECT COUNT(*) FROM t2) AS t2_count,
       (SELECT COUNT(*) FROM t3) AS t3_count
FROM   dual;

DELETE FROM t3;

rollback;

truncate table t1 ;

rollback;

truncate table t1 CASCADE;

sqlite级联删除

2 个答案: