SQL：返回列名，其中列包含给定值

Question

我想知道是否可以在SQL Server中运行一个命令/存储的程序，该程序将为我提供包含表中给定数据的列的名称。

因此，如果我要查询，请给我该表中所有包含值75的列。我不希望该行。只是表中的列名…这可能吗？

Answer 1

-- input parameters (guessing on type for @value):

DECLARE 
  @schema SYSNAME = N'dbo', 
  @table  SYSNAME = N'z', 
  @value  VARCHAR(64) = '75';


-- now, inside the procedure body:

DECLARE @sql NVARCHAR(MAX) = N'SELECT ''cols:'' + STUFF(''''';

SELECT @sql += N' 
  + CASE WHEN EXISTS (SELECT 1 FROM ' 
  + QUOTENAME(@schema) + '.' + QUOTENAME(@table)
  + ' WHERE TRY_CONVERT(VARCHAR(64), ' + QUOTENAME(c.name) 
  + ') = @value) THEN '', ' + c.name + ''' ELSE '''' END'
FROM sys.tables AS t
INNER JOIN sys.columns AS c
ON t.[object_id] = c.[object_id]
INNER JOIN sys.schemas AS s
ON t.[schema_id] = s.[schema_id]
WHERE t.name = @table AND s.name = @schema;

SET @sql += N', 1, 1, '''');'

PRINT @sql;

--EXEC sp_executesql @sql, N'@value VARCHAR(64)', @value;

当您对输出感到满意时，请取消注释EXEC。

因此，让我们考虑一个简单的表：

CREATE TABLE dbo.floob
(
  a INT, 
  b VARCHAR(32), 
  c VARBINARY(22), 
  d DATE, 
  e DATETIME, 
  f ROWVERSION
);

INSERT dbo.floob(a,b,c,d,e) VALUES
( 75, 'foo', 0x00, GETDATE(), GETDATE()),
( 21, '75',  0x00, GETDATE(), GETDATE());

现在，基于上述代码的存储过程：

CREATE PROCEDURE dbo.FindStringInAnyColumn
  @schema SYSNAME = N'dbo', 
  @table  SYSNAME,
  @value  VARCHAR(64)
AS
BEGIN
  SET NOCOUNT ON;

  DECLARE @sql NVARCHAR(MAX) = N'SELECT ''cols:'' + STUFF(''''';

  SELECT @sql += N' 
    + CASE WHEN EXISTS (SELECT 1 FROM ' 
    + QUOTENAME(@schema) + '.' + QUOTENAME(@table)
    + ' WHERE TRY_CONVERT(VARCHAR(64), ' + QUOTENAME(c.name) 
    + ') = @value) THEN '', ' + c.name + ''' ELSE '''' END'
  FROM sys.tables AS t
  INNER JOIN sys.columns AS c
  ON t.[object_id] = c.[object_id]
  INNER JOIN sys.schemas AS s
  ON t.[schema_id] = s.[schema_id]
  WHERE t.name = @table AND s.name = @schema;

  SET @sql += N', 1, 1, '''');'

  EXEC sp_executesql @sql, N'@value VARCHAR(64)', @value;
END
GO

用法示例：

EXEC dbo.FindStringInAnyColumn @table = N'floob', @value = '75';

输出：

Cols: a, b