更改 Microsoft SQL Server 中的主键列

Question

更新

以下是查询结果的约束

SELECT * FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE WHERE TABLE_NAME = 'history'

CONSTRAINT_NAME   COLUMN_NAME  ORDINAL_POSITION
PK_history        userKey       1
PK_history        name          2

这是查询结果

SELECT * 
FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS 
WHERE TABLE_NAME = 'history'

CONSTRAINT_NAME   CONSTRAINT_TYPE  IS_DEFERRABLE  INITIALLY_DEFERRED
PK_history        PRIMARY KEY      NO             NO

结束更新

我的主机通过 ASP.NET Enterprise Manager 提供到 SQL Server DB 的接口。

我的

history

表中有 3 列：

• userId

  （不允许使用 key、int、NULL）

• name

  （键、字符串、不允许为 NULL）

• id

  （不允许为 key、int、NULL）

我想让 id 列成为唯一的键。

要做到这一点，我相信我需要：

1. 确保任何行的该列中都没有 NULL
2. 将列设置为不允许 NULL
3. 将列添加为主键
4. 删除其他 2 列作为键

但是，当我使用提供的 UI 时，它永远不起作用。有时它看起来只是试图做某事，但当我刷新列的视图时它永远不会改变。它偶尔会创建一个临时表，看起来它试图执行某些操作，但它永远不会被复制/覆盖我试图更改的原始表。

当我尝试使用查询时，更改也不会显示。以下是我认为我需要的查询：

    SELECT * from history WHERE id is NULL     <---- This shows 0 results

    ALTER TABLE history
    ALTER COLUMN id int NOT NULL

    ALTER TABLE history ADD PRIMARY KEY (id)

    ALTER TABLE history
    DROP CONSTRAINT userId
    DROP CONSTRAINT name
    GO

我只是尝试禁止 NULL 并为 id 列添加主键。这似乎不起作用。有人能指出我正确的方向吗？谢谢！

Answer 1

假设您当前的主键约束名为 pk_history，您可以替换以下行：

ALTER TABLE history ADD PRIMARY KEY (id)

ALTER TABLE history
DROP CONSTRAINT userId
DROP CONSTRAINT name

与这些：

ALTER TABLE history DROP CONSTRAINT pk_history

ALTER TABLE history ADD CONSTRAINT pk_history PRIMARY KEY (id)

如果你不知道PK的名字是什么，可以通过以下查询找到它：

SELECT * 
  FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS 
 WHERE TABLE_NAME = 'history'

Answer 2

死灵魔法。
看起来你和我有一样好的模式可以使用...... 以下是正确的做法：

在此示例中，表名称为 dbo.T_SYS_Language_Forms，列名称为 LANG_UID

-- First, chech if the table exists...
IF 0 < (
    SELECT COUNT(*) FROM INFORMATION_SCHEMA.TABLES 
    WHERE TABLE_TYPE = 'BASE TABLE'
    AND TABLE_SCHEMA = 'dbo'
    AND TABLE_NAME = 'T_SYS_Language_Forms'
)
BEGIN
    -- Check for NULL values in the primary-key column
    IF 0 = (SELECT COUNT(*) FROM T_SYS_Language_Forms WHERE LANG_UID IS NULL)
    BEGIN
        ALTER TABLE T_SYS_Language_Forms ALTER COLUMN LANG_UID uniqueidentifier NOT NULL 

        -- No, don't drop, FK references might already exist...
        -- Drop PK if exists 
        -- ALTER TABLE T_SYS_Language_Forms DROP CONSTRAINT pk_constraint_name 
        --DECLARE @pkDropCommand nvarchar(1000) 
        --SET @pkDropCommand = N'ALTER TABLE T_SYS_Language_Forms DROP CONSTRAINT ' + QUOTENAME((SELECT CONSTRAINT_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS 
        --WHERE CONSTRAINT_TYPE = 'PRIMARY KEY' 
        --AND TABLE_SCHEMA = 'dbo' 
        --AND TABLE_NAME = 'T_SYS_Language_Forms' 
        ----AND CONSTRAINT_NAME = 'PK_T_SYS_Language_Forms' 
        --))
        ---- PRINT @pkDropCommand 
        --EXECUTE(@pkDropCommand) 

        -- Instead do
        -- EXEC sp_rename 'dbo.T_SYS_Language_Forms.PK_T_SYS_Language_Forms1234565', 'PK_T_SYS_Language_Forms';


        -- Check if they keys are unique (it is very possible they might not be) 
        IF 1 >= (SELECT TOP 1 COUNT(*) AS cnt FROM T_SYS_Language_Forms GROUP BY LANG_UID ORDER BY cnt DESC)
        BEGIN

            -- If no Primary key for this table
            IF 0 =  
            (
                SELECT COUNT(*) FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS 
                WHERE CONSTRAINT_TYPE = 'PRIMARY KEY' 
                AND TABLE_SCHEMA = 'dbo' 
                AND TABLE_NAME = 'T_SYS_Language_Forms' 
                -- AND CONSTRAINT_NAME = 'PK_T_SYS_Language_Forms' 
            )
                ALTER TABLE T_SYS_Language_Forms ADD CONSTRAINT PK_T_SYS_Language_Forms PRIMARY KEY CLUSTERED (LANG_UID ASC)
            ;

            -- Adding foreign key
            IF 0 = (SELECT COUNT(*) FROM INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS WHERE CONSTRAINT_NAME = 'FK_T_ZO_SYS_Language_Forms_T_SYS_Language_Forms') 
                ALTER TABLE T_ZO_SYS_Language_Forms WITH NOCHECK ADD CONSTRAINT FK_T_ZO_SYS_Language_Forms_T_SYS_Language_Forms FOREIGN KEY(ZOLANG_LANG_UID) REFERENCES T_SYS_Language_Forms(LANG_UID); 
        END -- End uniqueness check
        ELSE
            PRINT 'FSCK, this column has duplicate keys, and can thus not be changed to primary key...' 
    END -- End NULL check
    ELSE
        PRINT 'FSCK, need to figure out how to update NULL value(s)...' 
END