创建从多个表中删除数据的过程。 SQL 服务器

Question

我需要创建一个过程，允许我一次从多个表中删除数据，搜索 CUIT。这里显示了四个表格：

我必须传入一个 CUIT 值，如果它与数据库中保存的任何项目匹配，我需要将其删除。我找不到能够同时擦除两个以上表格的语法，如果你能帮我一把，我将不胜感激。我澄清了这个过程实际上要大得多的疑问，总共大约有 12 个表，但由于我只对语法感兴趣，所以我传递了这个片段。

我在尝试使用 INNER JOIN 连接表时遇到问题。

我正在使用 SQL Server 2016。谢谢

Answer 1

考虑到你的设计，我会在你的外键上实现级联。这是一个示例，但应该能让您走上正确的道路：

USE Sandbox;
GO

CREATE TABLE dbo.ParentTable (PK int IDENTITY PRIMARY KEY,
                              I int);

CREATE TABLE dbo.ChildTable1 (PK int IDENTITY PRIMARY KEY,
                              FK int,
                              S varchar(10));

CREATE TABLE dbo.ChildTable2 (PK int IDENTITY PRIMARY KEY,
                              FK int,
                              S varchar(10));

CREATE TABLE dbo.ChildTable3 (PK int IDENTITY PRIMARY KEY,
                              FK int,
                              S varchar(10));
GO
--Create keys with CASCADE ON DELETE
ALTER TABLE dbo.ChildTable1 ADD CONSTRAINT FK1 FOREIGN KEY (FK) REFERENCES dbo.ParentTable(PK) ON DELETE CASCADE;
GO
ALTER TABLE dbo.ChildTable2 ADD CONSTRAINT FK2 FOREIGN KEY (FK) REFERENCES dbo.ParentTable(PK) ON DELETE CASCADE;
GO
ALTER TABLE dbo.ChildTable3 ADD CONSTRAINT FK3 FOREIGN KEY (FK) REFERENCES dbo.ParentTable(PK) ON DELETE CASCADE;
GO


INSERT INTO dbo.ParentTable (I)
VALUES(1),(7),(9);

INSERT INTO dbo.ChildTable1 (FK,
                            S)
VALUES(1,'abc'),(3,'def');

INSERT INTO dbo.ChildTable2 (FK,
                            S)
VALUES(1,'xyz'),(2,'qwe');

INSERT INTO dbo.ChildTable3 (FK,
                            S)
VALUES(1,'123');
GO

SELECT *
FROM dbo.ParentTable PT
     LEFT JOIN dbo.ChildTable1 CT1 ON PT.PK = CT1.PK
     LEFT JOIN dbo.ChildTable2 CT2 ON PT.PK = CT2.PK
     LEFT JOIN dbo.ChildTable3 CT3 ON PT.PK = CT3.PK;

--1, as we're going to DELETE that
SELECT *
FROM dbo.ChildTable1 CT1
WHERE CT1.FK = 1;

SELECT *
FROM dbo.ChildTable1 CT2
WHERE CT2.FK = 1;

SELECT *
FROM dbo.ChildTable1 CT3
WHERE CT3.FK = 1;
GO

--Perform the DELETE, which will CASCADE to the child tables.    
DELETE FROM dbo.ParentTable
WHERE PK = 1;
GO
--no rows
SELECT *
FROM dbo.ParentTable PT
     LEFT JOIN dbo.ChildTable1 CT1 ON PT.PK = CT1.PK
     LEFT JOIN dbo.ChildTable2 CT2 ON PT.PK = CT2.PK
     LEFT JOIN dbo.ChildTable3 CT3 ON PT.PK = CT3.PK;

SELECT *
FROM dbo.ChildTable1 CT1
WHERE CT1.FK = 1;

SELECT *
FROM dbo.ChildTable1 CT2
WHERE CT2.FK = 1;

SELECT *
FROM dbo.ChildTable1 CT3
WHERE CT3.FK = 1;

GO
DROP TABLE dbo.ChildTable3;
DROP TABLE dbo.ChildTable2;
DROP TABLE dbo.ChildTable1;
DROP TABLE dbo.ParentTable;

Answer 2

如果您不想更改数据库架构，可以选择 INSTEAD OF TRIGGER。

触发器允许您在执行特定操作时执行任何任务。在这种情况下，您可以在 parent/master table 上编写 INSTEAD OF DELETE 触发器，在触发器内部您可以从 child table 中删除相关条目。看看下面的例子。

CREATE TABLE dbo.Gestiones
(
    id_gestione int IDENTITY (1, 1) PRIMARY KEY,
    CUIT INT
);

CREATE TABLE dbo.ChildGestione1
(
    ID INT IDENTITY PRIMARY KEY,
    id_gestioneFK int REFERENCES Gestiones(id_gestione),
    Description VARCHAR(100)
);

CREATE TABLE dbo.ChildGestione2
(
    ID INT IDENTITY PRIMARY KEY,
    id_gestioneFK int REFERENCES Gestiones(id_gestione),
    Description VARCHAR(100)
);

CREATE TABLE dbo.ChildGestione3
(
    ID INT IDENTITY PRIMARY KEY,
    id_gestioneFK int REFERENCES Gestiones(id_gestione),
    Description VARCHAR(100)
);


INSERT INTO dbo.Gestiones (CUIT)
VALUES (10), (20), (30), (40);

INSERT INTO dbo.ChildGestione1 (id_gestioneFK, Description)
VALUES (1,'abc'), (2,'efg');

INSERT INTO dbo.ChildGestione2 (id_gestioneFK, Description)
VALUES (1,'abc'), (3,'pqr');

INSERT INTO dbo.ChildGestione3 (id_gestioneFK, Description)
VALUES (1,'abc'), (3,'pqr'), (4,'stu');

GO


SELECT * FROM dbo.Gestiones
SELECT * FROM dbo.ChildGestione1
SELECT * FROM dbo.ChildGestione2
SELECT * FROM dbo.ChildGestione3

DELETE FROM Gestiones where CUIT = 10

SELECT * FROM dbo.Gestiones
SELECT * FROM dbo.ChildGestione1
SELECT * FROM dbo.ChildGestione2
SELECT * FROM dbo.ChildGestione3


CREATE TRIGGER InsteadOfDELETETriggerExample ON [Gestiones]
INSTEAD OF DELETE
AS 
BEGIN
    DECLARE @id_gestione INT

    SELECT @id_gestione = id_gestione FROM deleted

    IF @id_gestione IS NOT NULL
    BEGIN
        DELETE FROM ChildGestione1 WHERE id_gestioneFK = @id_gestione
        DELETE FROM ChildGestione2 WHERE id_gestioneFK = @id_gestione
        DELETE FROM ChildGestione3 WHERE id_gestioneFK = @id_gestione
        /*...
        and so on...you can right as many child tables as you have
        */

        -- At the last, delete the entry from parent table
        DELETE FROM Gestiones WHERE id_gestione = @id_gestione
    END

    PRINT 'Successfully deleted references of CUIT column from all the child tables.'
END
GO


DROP TRIGGER InsteadOfDELETETriggerExample
GO

DROP TABLE dbo.ChildGestione3;
DROP TABLE dbo.ChildGestione2;
DROP TABLE dbo.ChildGestione1;
DROP TABLE dbo.Gestiones;

以上代码仅适用于 master table 上的一个删除条目，如果删除操作影响 parent table 中的多个条目，则您需要 JOIN deleted table 用你的 child table 删除。

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