Question

我有一个单调乏味的情况，我正在寻找一种“不那么乏味”的方式。

目前，我被要求从数据库中删除一些数据 - 没什么大不了的，这很容易吗？错。

这个数据库我没有参与过，所以我不熟悉主/外键关系，这是一个单调乏味的部分，因为大约有15-20个表非常错综复杂地连接在一起。

在不知道PK / FK关系的情况下删除索引数据的最快方法是什么，并且必须逐个DELETE FROM ... WHERE [something] = [somethingElse]并根据另一个表的键找出它？

Answer 1

您可以查询sys.foreign_keys系统视图以获取有关所有FK关系的信息。从那里创建DROP和CREATE语句并不过分。

我有一个函数可以为partiuclar表的所有FK返回各种语句（例如DROP，CREATE，CHECK）。在Management Studio中运行此函数并将结果返回到Text可以为您提供格式良好的语句，以便轻松删除所有FK，删除数据，然后再将FK添加回来。

希望您可以根据自己的需要量身定制。

希望它有所帮助，

灰

CREATE FUNCTION [utils].[uf_ForeignKeyScripts]
    (
@PrimaryKeyTable        varchar(128) 
,   @PrimaryKeyTableSchema  varchar(32)
)
RETURNS @Scripts TABLE 
    (
    ForeignKeyName          varchar(64)
,   IfExistsStatement       varchar(1000)
,   DropStatement           varchar(1000)
,   IfNotExistsStatement    varchar(1000)
,   CreateStatement         varchar(1000)
,   CheckStatement          varchar(1000)
,   NoCheckStatement        varchar(1000)
    )
    AS

/*
This function returns statements used to create, drop, and check all Foreign Key constraints that reference a given table.
These statements can be then added to T-SQL scripts.

Example usage (ensure selection of the Results to Text option in SSMS) :

1) To create statements to check all foreign keys

SELECT
    IfExistsStatement + CHAR(13) +
    CHAR(9) + CheckStatement + CHAR(13)
FROM
    utils.uf_ForeignKeyScripts('t_Dim_Date','dbo')      
    ;

This will return a formatted statement to check the existence of a foreign key and if it exists, check that data does not violate the key.

*/

BEGIN
    INSERT INTO
        @Scripts
        (
        ForeignKeyName
    ,   IfExistsStatement
    ,   DropStatement
    ,   IfNotExistsStatement
    ,   CreateStatement
    ,   CheckStatement
    ,   NoCheckStatement
        )
    SELECT
        FK.name AS ForeignKeyName
    ,   'IF EXISTS (SELECT * FROM sys.foreign_keys WHERE object_id = OBJECT_ID(N''' + SFK.name + '.' + FK.name + ''') ' + 
        'AND parent_object_id = OBJECT_ID(N''' + SFK.name + '.' + OBJECT_NAME(FK.parent_object_id) + '''))'
        AS IfExistsStatement
    ,   'ALTER TABLE ' + SFK.name + '.' + OBJECT_NAME(FK.parent_object_id) + ' ' + 
        'DROP CONSTRAINT ' + FK.name + CHAR(13) + ';' 
        AS DropStatement
    ,   'IF NOT EXISTS (SELECT * FROM sys.foreign_keys WHERE object_id = OBJECT_ID(N''' + SFK.name + '.' + FK.name + ''') ' + 
        'AND parent_object_id = OBJECT_ID(N''' + SFK.name + '.' + OBJECT_NAME(FK.parent_object_id) + '''))'
        AS IfNotExistsStatement 
    ,   'ALTER TABLE ' + SFK.name + '.' + OBJECT_NAME(FK.parent_object_id) + ' ' +
        'WITH CHECK ADD CONSTRAINT ' + FK.name + ' ' + 
        'FOREIGN KEY (' + C.FKColumns + ') ' + 
        'REFERENCES ' + ST.name + '.' + OBJECT_NAME(fk.referenced_object_id) + ' ' + 
        '(' + C.FKColumns + ')' + CHAR(13) + ';' 
        AS CreateStatement
    ,   'ALTER TABLE ' + SFK.name + '.' + OBJECT_NAME(FK.parent_object_id) + ' ' +
        'CHECK CONSTRAINT ' + FK.name + CHAR(13) + ';'
        AS CheckStatement
    ,   'ALTER TABLE ' + SFK.name + '.' + OBJECT_NAME(FK.parent_object_id) + ' ' +
        'NOCHECK CONSTRAINT ' + FK.name +   CHAR(13) + ';'
        AS NoCheckStatement
    FROM
        sys.foreign_keys AS FK
    INNER JOIN
        sys.schemas AS SFK -- schema of foreign key table
    ON
        FK.schema_id = SFK.schema_id
    INNER JOIN
        sys.tables AS T -- primary key table
    ON
        FK.referenced_object_id = T.object_id
    INNER JOIN
        sys.schemas AS ST -- schema of primary key table
    ON
        T.schema_id = ST.schema_id
    CROSS APPLY
        (
        /* Get all columns to handle composite keys */
        SELECT 
            SFKC.constraint_object_id
        ,   utils.uf_ConcatanateStringWithDelimiter(COL_NAME(SFKC.referenced_object_id, SFKC.referenced_column_id),', ') AS FKColumns
        FROM
            sys.foreign_key_columns AS SFKC
        WHERE
            SFKC.constraint_object_id = FK.object_id
        GROUP BY
            SFKC.constraint_object_id
        )
        AS C
    WHERE
        OBJECT_NAME(T.object_id) = @PrimaryKeyTable
    AND ST.name = @PrimaryKeyTableSchema
    ;
    RETURN 
END

删除不熟悉的数据库上的数据

1 个答案: