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
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_SCALEFROM [INFORMATION_SCHEMA].[COLUMNS] cWHERE 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_DEFAULTFROM [INFORMATION_SCHEMA].[COLUMNS] cWHERE 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_KEYFROM [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_NAMEWHERE 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_TABLEFROM [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_NAMEWHERE 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_TABLEFROM [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_NAMEWHERE 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！
