探讨SQL利用INFORMATION_SCHEMA系统视图如何获取表的主外键信息

 更新时间:2013年06月21日 11:15:02   作者:  
本篇文章是对SQL利用INFORMATION_SCHEMA系统视图如何获取表的主外键信息进行了详细的分析介绍,需要的朋友参考下
接着上篇文章《解析SQL 表结构信息查询 含主外键、自增长》里面提到了INFORMATION_SCHEMA视图,其实到了SQL 2005微软都主推大家使用INFORMATION_SCHEMA系统视图,而不是在使用sys东东了,当然目前还是有许多信息只能通过sys视图来查询。这里我们还是以查询表结果信息为例来说明一些主要的INFORMATION_SCHEMA视图的使用。
首先我们需要查询列的信息,这需要用到[INFORMATION_SCHEMA].[COLUMNS]系统视图来查询数据列的信息,SQL 如下:
复制代码 代码如下:

SELECT  c.TABLE_SCHEMA ,
        c.TABLE_NAME ,
        c.COLUMN_NAME ,
        c.DATA_TYPE ,
        c.CHARACTER_MAXIMUM_LENGTH ,
        c.COLUMN_DEFAULT ,
        c.IS_NULLABLE ,
        c.NUMERIC_PRECISION ,
        c.NUMERIC_SCALE
FROM    [INFORMATION_SCHEMA].[COLUMNS] c
WHERE   TABLE_NAME = 'Address'

运行结果如下:

我们都知道我们在定义列的时候一般的使用都是varchar(50)之类的信息,这里我们需要整合DATA_TYPE和CHARACTER_MAXIMUM_LENGTH信息,当CHARACTER_MAXIMUM_LENGTH为-1时即使说没有指定具体最大长度,数据的指定长度信息是max,而numeric需要整合NUMERIC_PRECISION、NUMERIC_SCALE信息。修改后的SQL如下:
复制代码 代码如下:

SELECT  c.TABLE_SCHEMA ,
        c.TABLE_NAME ,
        c.COLUMN_NAME ,
        CASE WHEN ( ( CHARINDEX('char', c.DATA_TYPE) > 0
                      OR CHARINDEX('binary', c.DATA_TYPE) > 0
                    )
                    AND c.CHARACTER_MAXIMUM_LENGTH <> -1
                  )
             THEN c.DATA_TYPE + '('
                  + CAST(c.CHARACTER_MAXIMUM_LENGTH AS VARCHAR(4)) + ')'
             WHEN ( ( CHARINDEX('CHAR', c.DATA_TYPE) > 0
                      OR CHARINDEX('binary', c.DATA_TYPE) > 0
                    )
                    AND c.CHARACTER_MAXIMUM_LENGTH = -1
                  ) THEN c.DATA_TYPE + '(max)'
             WHEN ( CHARINDEX('numeric', c.DATA_TYPE) > 0 )
             THEN c.DATA_TYPE + '(' + CAST(c.NUMERIC_PRECISION AS VARCHAR(4))
                  + ',' + CAST(c.NUMERIC_SCALE AS VARCHAR(4)) + ')'
             ELSE c.DATA_TYPE
        END AS DATA_TYPE ,
        c.COLUMN_DEFAULT ,
        c.IS_NULLABLE ,
        c.COLUMN_DEFAULT
FROM    [INFORMATION_SCHEMA].[COLUMNS] c
WHERE   TABLE_NAME = 'Address'
ORDER BY c.ORDINAL_POSITION

运行结果如图:

现在我们需要标记这张表的那些列是主键,那些列是外键,要查询表的主、外键信息需要用到[INFORMATION_SCHEMA].[TABLE_CONSTRAINTS]和[INFORMATION_SCHEMA].[KEY_COLUMN_USAGE] 系统视图
运行结果如图:

修改我们先前的SQL语句:
复制代码 代码如下:

SELECT  c.TABLE_SCHEMA ,
        c.TABLE_NAME ,
        c.COLUMN_NAME ,
        CASE WHEN ( ( CHARINDEX('char', c.DATA_TYPE) > 0
                      OR CHARINDEX('binary', c.DATA_TYPE) > 0
                    )
                    AND c.CHARACTER_MAXIMUM_LENGTH <> -1
                  )
             THEN c.DATA_TYPE + '('
                  + CAST(c.CHARACTER_MAXIMUM_LENGTH AS VARCHAR(4)) + ')'
             WHEN ( ( CHARINDEX('CHAR', c.DATA_TYPE) > 0
                      OR CHARINDEX('binary', c.DATA_TYPE) > 0
                    )
                    AND c.CHARACTER_MAXIMUM_LENGTH = -1
                  ) THEN c.DATA_TYPE + '(max)'
             WHEN ( CHARINDEX('numeric', c.DATA_TYPE) > 0 )
             THEN c.DATA_TYPE + '(' + CAST(c.NUMERIC_PRECISION AS VARCHAR(4))
                  + ',' + CAST(c.NUMERIC_SCALE AS VARCHAR(4)) + ')'
             ELSE c.DATA_TYPE
        END AS DATA_TYPE ,
        c.COLUMN_DEFAULT ,
        c.IS_NULLABLE ,
        c.COLUMN_DEFAULT ,
        CASE WHEN tc.CONSTRAINT_TYPE = 'PRIMARY KEY' THEN 'YES'
             ELSE 'NO'
        END AS IS_PRIMARY_KEY ,
        CASE WHEN tc.CONSTRAINT_TYPE = 'FOREIGN KEY' THEN 'YES'
             ELSE 'NO'
        END AS IS_FOREIGN_KEY
FROM    [INFORMATION_SCHEMA].[COLUMNS] c
        LEFT JOIN [INFORMATION_SCHEMA].[KEY_COLUMN_USAGE] kcu ON kcu.TABLE_SCHEMA = c.TABLE_SCHEMA
                                                              AND kcu.TABLE_NAME = c.TABLE_NAME
                                                              AND kcu.COLUMN_NAME = c.COLUMN_NAME
        LEFT JOIN [INFORMATION_SCHEMA].[TABLE_CONSTRAINTS] tc ON tc.CONSTRAINT_SCHEMA = kcu.CONSTRAINT_SCHEMA
                                                              AND tc.CONSTRAINT_NAME = kcu.CONSTRAINT_NAME
WHERE   c.TABLE_NAME = 'Address'
ORDER BY c.ORDINAL_POSITION

运行结果如图:

现在我们已经知道那些列是主键那些是外键,接下来的就是外键列所关联的外检表信息,这里需要用到[INFORMATION_SCHEMA].[REFERENTIAL_CONSTRAINTS]系统视图,运行该视图如下:

所以修改我们的SQL如下:
复制代码 代码如下:

SELECT  c.TABLE_SCHEMA ,
        c.TABLE_NAME ,
        c.COLUMN_NAME ,
        CASE WHEN ( ( CHARINDEX('char', c.DATA_TYPE) > 0
                      OR CHARINDEX('binary', c.DATA_TYPE) > 0
                    )
                    AND c.CHARACTER_MAXIMUM_LENGTH <> -1
                  )
             THEN c.DATA_TYPE + '('
                  + CAST(c.CHARACTER_MAXIMUM_LENGTH AS VARCHAR(4)) + ')'
             WHEN ( ( CHARINDEX('CHAR', c.DATA_TYPE) > 0
                      OR CHARINDEX('binary', c.DATA_TYPE) > 0
                    )
                    AND c.CHARACTER_MAXIMUM_LENGTH = -1
                  ) THEN c.DATA_TYPE + '(max)'
             WHEN ( CHARINDEX('numeric', c.DATA_TYPE) > 0 )
             THEN c.DATA_TYPE + '(' + CAST(c.NUMERIC_PRECISION AS VARCHAR(4))
                  + ',' + CAST(c.NUMERIC_SCALE AS VARCHAR(4)) + ')'
             ELSE c.DATA_TYPE
        END AS DATA_TYPE ,
        c.COLUMN_DEFAULT ,
        c.IS_NULLABLE ,
        c.COLUMN_DEFAULT ,
        CASE WHEN tc.CONSTRAINT_TYPE = 'PRIMARY KEY' THEN 'YES'
             ELSE 'NO'
        END AS IS_PRIMARY_KEY ,
        CASE WHEN tc.CONSTRAINT_TYPE = 'FOREIGN KEY' THEN 'YES'
             ELSE 'NO'
        END AS IS_FOREIGN_KEY,
        fkcu.COLUMN_NAME AS FOREIGN_KEY,
        fkcu.TABLE_NAME AS FOREIGN_TABLE
FROM    [INFORMATION_SCHEMA].[COLUMNS] c
        LEFT JOIN [INFORMATION_SCHEMA].[KEY_COLUMN_USAGE] kcu ON kcu.TABLE_SCHEMA = c.TABLE_SCHEMA
                                                              AND kcu.TABLE_NAME = c.TABLE_NAME
                                                              AND kcu.COLUMN_NAME = c.COLUMN_NAME
        LEFT JOIN [INFORMATION_SCHEMA].[TABLE_CONSTRAINTS] tc ON tc.CONSTRAINT_SCHEMA = kcu.CONSTRAINT_SCHEMA
                                                              AND tc.CONSTRAINT_NAME = kcu.CONSTRAINT_NAME
        LEFT JOIN [INFORMATION_SCHEMA].[REFERENTIAL_CONSTRAINTS] fc ON kcu.CONSTRAINT_SCHEMA = fc.CONSTRAINT_SCHEMA
                                                              AND kcu.CONSTRAINT_NAME = fc.CONSTRAINT_NAME
        LEFT JOIN [INFORMATION_SCHEMA].[KEY_COLUMN_USAGE] fkcu ON fkcu.CONSTRAINT_SCHEMA = fc.UNIQUE_CONSTRAINT_SCHEMA
                                                              AND fkcu.CONSTRAINT_NAME = fc.UNIQUE_CONSTRAINT_NAME
WHERE   c.TABLE_NAME = 'Address'
ORDER BY c.ORDINAL_POSITION

运行结果如图:

我们的查询结果中显示了太多的NULL,看着不怎么舒服,还有我们的表名应该显示一次就可以,修改SQL如下:
复制代码 代码如下:

SELECT  CASE WHEN c.ORDINAL_POSITION = 1
             THEN c.TABLE_SCHEMA + '.' + c.TABLE_NAME
             ELSE ''
        END AS TABLE_NAME ,
        c.COLUMN_NAME ,
        CASE WHEN ( ( CHARINDEX('char', c.DATA_TYPE) > 0
                      OR CHARINDEX('binary', c.DATA_TYPE) > 0
                    )
                    AND c.CHARACTER_MAXIMUM_LENGTH <> -1
                  )
             THEN c.DATA_TYPE + '('
                  + CAST(c.CHARACTER_MAXIMUM_LENGTH AS VARCHAR(4)) + ')'
             WHEN ( ( CHARINDEX('CHAR', c.DATA_TYPE) > 0
                      OR CHARINDEX('binary', c.DATA_TYPE) > 0
                    )
                    AND c.CHARACTER_MAXIMUM_LENGTH = -1
                  ) THEN c.DATA_TYPE + '(max)'
             WHEN ( CHARINDEX('numeric', c.DATA_TYPE) > 0 )
             THEN c.DATA_TYPE + '(' + CAST(c.NUMERIC_PRECISION AS VARCHAR(4))
                  + ',' + CAST(c.NUMERIC_SCALE AS VARCHAR(4)) + ')'
             ELSE c.DATA_TYPE
        END AS DATA_TYPE ,
        ISNULL(c.COLUMN_DEFAULT, '') AS COLUMN_DEFAULT ,
        CASE WHEN c.IS_NULLABLE = 'YES' THEN '√'
             ELSE ''
        END IS_NULLABLE ,
        CASE WHEN tc.CONSTRAINT_TYPE = 'PRIMARY KEY' THEN '√'
             ELSE ''
        END AS IS_PRIMARY_KEY ,
        CASE WHEN tc.CONSTRAINT_TYPE = 'FOREIGN KEY' THEN '√'
             ELSE ''
        END AS IS_FOREIGN_KEY ,
        ISNULL(fkcu.COLUMN_NAME, '') AS FOREIGN_KEY ,
        ISNULL(fkcu.TABLE_NAME, '') AS FOREIGN_TABLE
FROM    [INFORMATION_SCHEMA].[COLUMNS] c
        LEFT JOIN [INFORMATION_SCHEMA].[KEY_COLUMN_USAGE] kcu ON kcu.TABLE_SCHEMA = c.TABLE_SCHEMA
                                                              AND kcu.TABLE_NAME = c.TABLE_NAME
                                                              AND kcu.COLUMN_NAME = c.COLUMN_NAME
        LEFT JOIN [INFORMATION_SCHEMA].[TABLE_CONSTRAINTS] tc ON tc.CONSTRAINT_SCHEMA = kcu.CONSTRAINT_SCHEMA
                                                              AND tc.CONSTRAINT_NAME = kcu.CONSTRAINT_NAME
        LEFT JOIN [INFORMATION_SCHEMA].[REFERENTIAL_CONSTRAINTS] fc ON kcu.CONSTRAINT_SCHEMA = fc.CONSTRAINT_SCHEMA
                                                              AND kcu.CONSTRAINT_NAME = fc.CONSTRAINT_NAME
        LEFT JOIN [INFORMATION_SCHEMA].[KEY_COLUMN_USAGE] fkcu ON fkcu.CONSTRAINT_SCHEMA = fc.UNIQUE_CONSTRAINT_SCHEMA
                                                              AND fkcu.CONSTRAINT_NAME = fc.UNIQUE_CONSTRAINT_NAME
WHERE   c.TABLE_NAME = 'Address'
ORDER BY c.ORDINAL_POSITION


运行结果如图:

有不对的地方还请大家拍砖!

相关文章

  • MySQL 学习总结 之 初步了解 InnoDB 存储引擎的架构设计

    MySQL 学习总结 之 初步了解 InnoDB 存储引擎的架构设计

    这篇文章主要介绍了MySQL 学习总结 之 初步了解 InnoDB 存储引擎的架构设计,文中给大家提到了mysql存储引擎有哪些,本文给大家介绍的非常详细,需要的朋友可以参考下
    2020-02-02
  • MySQL性能分析及explain的使用说明

    MySQL性能分析及explain的使用说明

    本文我们主要介绍了MySQL性能分析以及explain的使用,包括:组合索引、慢查询分析、MYISAM和INNODB的锁定、MYSQL的事务配置项等,希望能够对您有所帮助。
    2011-08-08
  • MySQL系列之十五 MySQL常用配置和性能压力测试

    MySQL系列之十五 MySQL常用配置和性能压力测试

    今天给大家带来一篇教程关于MySQL常用配置和性能压力测试的知识,文中配置参数以32内存的服务器为例,通过实例代码给大家介绍的非常详细,需要的朋友参考下吧
    2021-07-07
  • mysql 触发器用法实例详解

    mysql 触发器用法实例详解

    这篇文章主要介绍了mysql 触发器用法实例详解的相关资料,需要的朋友可以参考下
    2017-06-06
  • SQL函数将某个字段合并在一起的操作

    SQL函数将某个字段合并在一起的操作

    这篇文章主要介绍了SQL函数将某个字段合并在一起的操作,具有很好的参考价值,希望对大家有所帮助。一起跟随小编过来看看吧
    2021-01-01
  • win10下mysql5.7.21解压版安装教程

    win10下mysql5.7.21解压版安装教程

    这篇文章主要为大家详细介绍了win10下mysql5.7.21解压版安装教程,具有一定的参考价值,感兴趣的小伙伴们可以参考一下
    2018-02-02
  • mysql 8.0.15 安装配置图文教程

    mysql 8.0.15 安装配置图文教程

    这篇文章主要为大家详细介绍了mysql 8.0.15 安装配置图文教程,具有一定的参考价值,感兴趣的小伙伴们可以参考一下
    2019-03-03
  • mysql中profile的使用方法教程

    mysql中profile的使用方法教程

    这篇文章主要给大家介绍了关于mysql中profile的使用方法,文中通过示例代码介绍的非常详细,对大家的学习或者工作具有一定的参考学习价值,需要的朋友们下面随着小编来一起学习学习吧
    2018-09-09
  • 详解MySQL 5.7 MGR单主确定主节点方法

    详解MySQL 5.7 MGR单主确定主节点方法

    这篇文章主要介绍了详解MySQL 5.7 MGR单主确定主节点方法,文中通过示例代码介绍的非常详细,对大家的学习或者工作具有一定的参考学习价值,需要的朋友们下面随着小编来一起学习学习吧
    2019-09-09
  • mysql出现提示错误10061的解决方法

    mysql出现提示错误10061的解决方法

    这篇文章主要为大家详细介绍了mysql出现提示错误10061的解决方法,具有一定的参考价值,感兴趣的小伙伴们可以参考一下
    2017-10-10

最新评论