什么时候Cascade在Sqlite中删除提交？

Question

这是我的sql语句集：

char *sql = "BEGIN TRANSACTION;
CREATE TABLE Friends(id varchar UNIQUE); 
CREATE TABLE Enemies(id2 varchar ,id3 INTEGER,CONSTRAINT id_econst
FOREIGN KEY(id2) REFERENCES Friends(id) ON DELETE CASCADE);
INSERT INTO Friends VALUES('11');
INSERT INTO Friends VALUES('2');
INSERT INTO Enemies VALUES('11',3);
INSERT INTO Enemies VALUES('3',5);
END TRANSACTION;
PRAGMA foreign_keys = ON;
DELETE FROM Friends WHERE id = '11';";

在Enemies表上执行级联删除，而：

 char *sql = "BEGIN TRANSACTION;
CREATE TABLE Friends(id varchar UNIQUE); 
CREATE TABLE Enemies(id2 varchar ,id3 INTEGER,CONSTRAINT id_econst
FOREIGN KEY(id2) REFERENCES Friends(id) ON DELETE CASCADE);
INSERT INTO Friends VALUES('11');
INSERT INTO Friends VALUES('2');
INSERT INTO Enemies VALUES('11',3);
INSERT INTO Enemies VALUES('3',5);
PRAGMA foreign_keys = ON;
DELETE FROM Friends WHERE id = '11';
END TRANSACTION;";

正常删除。

为什么会这样？

Answer 1

您正在事务中启用外键支持。引用sqlite：

  

此pragma是事务中的无操作

https://sqlite.org/pragma.html#pragma_foreign_keys

在第二个示例中，pragma无效，并且不强制执行外键约束。