[英]query columns from many tables using dynamic SQL or Correlated Subquery on SQL Server INFORMATION_SCHEMA
I want to list all the Manufacturers
identified in an SQL Server database. 我想列出SQL Server数据库中标识的所有
Manufacturers
。
There are many tables with manufacturer names in them, but they are not always in a nicely named column. 有许多表中包含制造商名称,但它们并不总是在一个名称很好的列中。 However, column names are LIKE
%manuf%
. 但是,列名称为 LIKE
%manuf%
。
So: 所以:
SELECT TABLE_NAME, COLUMN_NAME
FROM INFORMATION_SCHEMA.COLUMNS
WHERE COLUMN_NAME LIKE '%manuf%'
ORDER BY TABLE_NAME;
gets me a list of tables I want to query from and the column name I want to query. 获取我想要查询的表的列表以及我想要查询的列名。
How can I now query the manufacturer names from those tables? 我现在如何从这些表中查询制造商名称?
If you want all of them returned in one result set you can use this query: 如果您希望在一个结果集中返回所有这些,则可以使用此查询:
DECLARE @cmd NVARCHAR(MAX);
SET @cmd = STUFF((
SELECT ' UNION ALL SELECT '+QUOTENAME(COLUMN_NAME)+' FROM '+QUOTENAME(TABLE_NAME)
FROM INFORMATION_SCHEMA.COLUMNS
WHERE COLUMN_NAME LIKE '%manuf%'
ORDER BY TABLE_NAME
FOR XML PATH(''),TYPE
).value('.','NVARCHAR(MAX)'),1,11,'')
;
EXEC( @cmd);
That requires all of them to be a (n)varchar data type. 这要求所有这些都是(n)varchar数据类型。 If you run into problems add a cast:
如果遇到问题,请添加一个演员:
SELECT ' UNION ALL SELECT CAST('+QUOTENAME(COLUMN_NAME)+' AS NVARCHAR(MAX)) FROM '+QUOTENAME(TABLE_NAME)
This seems like a very odd database design. 这似乎是一个非常奇怪的数据库设计。 You might want to revisit that...
你可能想重新审视......
If INFORMATION_SCHEMA
isn't working for you use this: 如果
INFORMATION_SCHEMA
不适用于您,请使用此:
DECLARE @cmd NVARCHAR(MAX);
SET @cmd = STUFF((
SELECT ' UNION ALL SELECT '+QUOTENAME(c.name)+' FROM dbo.'+QUOTENAME(t.name)
FROM sys.columns c
JOIN sys.tables t
ON c.object_id = t.object_id
WHERE c.name LIKE '%name%'
AND t.is_ms_shipped = 0
ORDER BY t.name
FOR XML PATH(''),TYPE
).value('.','NVARCHAR(MAX)'),1,11,'')
;
EXEC( @cmd);
While INFORMATION_SCHEMA
is part of the ANSI standard, using the SQL Server catalog views is usually the preferred way to go anyway. 虽然
INFORMATION_SCHEMA
是ANSI标准的一部分,但使用SQL Server目录视图通常是首选的方法。
One more thing: If INFORMATION_SCHEMA
returns incorrect results, you might have some kind of corruption going on, you should check that by running DBCC CHECKDB
in that database. 还有一件事:如果
INFORMATION_SCHEMA
返回不正确的结果,您可能会遇到某种类型的损坏,您应该通过在该数据库中运行DBCC CHECKDB
来检查它。
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