Question

我有两张表定义如下;从用户表，hospitalId和poliklinikId都引用表relhospol，如果从relhospol删除任何行（如果有任何用户与之相关），我想设置hospitalId和poliklinikId为null，DDL说。当我从SQLite Manager中删除一行时，它会使用户的hospitalId和PoliklinikId为空，但是当我尝试从应用程序级别（Java）中删除一行时，它只从relhospol中删除，它没有设置null（hospitalId，PoliklinikId）是什么遗漏点？
JDBC驱动程序：SQLite-jdbc-3.7.2

CREATE TABLE [USER] (
  [ID] INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, 
  [GROUPID] INTEGER CONSTRAINT [FK_USER_GID] REFERENCES [GROUP]([ID]) ON DELETE SET NULL ON UPDATE CASCADE, 
  [HOSPITALID] INTEGER, 
  [POLIKLINIKID] INTEGER, 
  [NAME] VARCHAR(50) NOT NULL, 
  [LOGINID] VARCHAR(15) NOT NULL, 
  [EMAIL] VARCHAR(50) NOT NULL, 
  [PASSWORD] VARCHAR(32) NOT NULL, 
  CONSTRAINT [FK_USER_RELHOSPOL] FOREIGN KEY([HOSPITALID], [POLIKLINIKID]) REFERENCES [RELHOSPOL]([HOSPITALID], [POLIKLINIKID]) ON DELETE SET NULL ON UPDATE CASCADE);

CREATE UNIQUE INDEX [AS] ON [USER] ([LOGINID]);
CREATE UNIQUE INDEX [AS1] ON [USER] ([EMAIL]));

CREATE TABLE [RELHOSPOL] (
  [HOSPITALID] INTEGER CONSTRAINT [FK_RELHOSPOL_HOS] REFERENCES [HOSPITAL]([ID]) ON DELETE SET NULL ON UPDATE CASCADE, 
  [POLIKLINIKID] INTEGER CONSTRAINT [FK_RELHOSPOL_POL] REFERENCES [POLIKLINIK]([ID]) ON DELETE SET NULL ON UPDATE CASCADE, 
  CONSTRAINT [sqlite_autoindex_RELHOSPOL_1] PRIMARY KEY ([HOSPITALID], [POLIKLINIKID]));

Answer 1

您无法将NULL设置为主键：

CREATE TABLE [RELHOSPOL] (
[HOSPITALID] INTEGER CONSTRAINT [FK_RELHOSPOL_HOS] REFERENCES [HOSPITAL]([ID]) ON DELETE SET NULL ON UPDATE CASCADE, 
[POLIKLINIKID] INTEGER CONSTRAINT [FK_RELHOSPOL_POL] REFERENCES [POLIKLINIK]([ID]) ON DELETE SET NULL ON UPDATE CASCADE, 
CONSTRAINT [sqlite_autoindex_RELHOSPOL_1] PRIMARY KEY ([HOSPITALID], [POLIKLINIKID]));

您是要尝试从哪个表中删除一行？你能发布DELETE SQL吗？

Answer 2

好的我已经改变了RELHOSPOL的定义如下;当我通过执行DELETE命令从SQL管理器中删除RELHOSPOL中的行时，它会使USER表中的必要行为空。每当我使用下面编写的方法从应用程序中删除一行时，它只从RELHOSPOL中删除行，并且在USER表中没有SET NULL必要的行

CREATE TABLE [RELHOSPOL] (
  [ID] INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, 
  [HOSPITALID] INTEGER, 
  [POLIKLINIKID] INTEGER);

CREATE UNIQUE INDEX [UNIQUE_RELHOSPOL] ON [RELHOSPOL] ([HOSPITALID], [POLIKLINIKID]);

删除方法是：

public void deletePoliklinikFromHospital(int hospitalId, int poliklinikId) throws SQLException{
        String query = "DELETE FROM [RELHOSPOL] WHERE (HOSPITALID = ? AND POLIKLINIKID = ?)";
        try {
            PreparedStatement statement = db.prepareStatement(query);
            statement.setInt(1, hospitalId);
            statement.setInt(2, poliklinikId);
            statement.executeUpdate();
        } catch (SQLException e) {
            throw new SQLException(e.getMessage());
        }
    }

Answer 3

这只是猜测，但也许您不知道，每次连接数据库时都必须enable foreign key support PRAGMA foreign_keys = ON;？如果不这样做，您的语句将被解析，但不会被强制执行。这可以解释为什么它来自SQLite Manager。

还应该知道，旧版本的Sqlite（＆lt; 3.6.19）将容忍语法，但也不会强制执行任何操作。

作为旁注：正如@Neuquino写表ON DELETE SET NULL的{{1}}语句似乎没有意义。

删除时出现外键问题

3 个答案: