Sql server 2008 查询运行方式存储过程（sp_sqlexec）不提供任何结果（T-SQL、SQL Server）

我想运行一个查询，显示数据库中所有表的所有列，数据类型为

varchar

，最大长度为8000个字符

这是到目前为止我的代码

DECLARE @tabs VARCHAR(MAX);

SET @tabs = 
(
  SELECT STUFF(( SELECT DISTINCT ',' + [TABLE_NAME]
                 FROM [DB-Test].INFORMATION_SCHEMA.COLUMNS 
                 WHERE DATA_TYPE = 'VARCHAR' AND
                       CHARACTER_MAXIMUM_LENGTH = 8000
                 FOR XML PATH('')), 1, 1, '')
);

DECLARE @cols VARCHAR(MAX)
SET @cols = 
(
  SELECT STUFF(( SELECT DISTINCT ',' + [TABLE_NAME] + '.' + [COLUMN_NAME]
                 FROM [DB-Test].INFORMATION_SCHEMA.COLUMNS 
                 WHERE DATA_TYPE = 'VARCHAR' AND
                       CHARACTER_MAXIMUM_LENGTH = 8000
                 FOR XML PATH('')), 1, 1, '')
);

DECLARE @query VARCHAR(MAX) = 'SELECT ' + @cols + ' FROM ' + @tabs

EXEC sp_sqlexec @query

当我运行查询时，我得到所有的列名，但不是列中的值。它是空的。没有“空”值。好像@cols被解释为简单的字符串。 为什么?

---

（当我读出@cols和@tabs时，它们是正确的。）

我猜您的数据库中有一个表，它的列具有VARCHAR数据类型和8000长度，但该表没有任何记录。尝试只包括至少有一条记录可用的列和表

你可以在下面试试。检查一下，让我知道它是否有效

DECLARE @tabs VARCHAR(MAX) = ''

; WITH CTE AS 
(
 SELECT DISTINCT TA.NAME TABLENAME
      , SUM(PA.ROWS) OVER (PARTITION BY TA.NAME ) NOOFROW
 FROM SYS.TABLES TA
 INNER JOIN SYS.PARTITIONS PA ON PA.OBJECT_ID = TA.OBJECT_ID
 INNER JOIN SYS.SCHEMAS SC ON TA.SCHEMA_ID = SC.SCHEMA_ID
 WHERE TA.IS_MS_SHIPPED = 0 AND PA.INDEX_ID IN (1,0) 
), TABLENAME AS
(
    SELECT ITBL.[TABLE_NAME]
    FROM INFORMATION_SCHEMA.COLUMNS ITBL
    WHERE ITBL.DATA_TYPE = 'VARCHAR' AND
          ITBL.CHARACTER_MAXIMUM_LENGTH = 8000  
          AND EXISTS(SELECT 1 FROM CTE WHERE CTE.TABLENAME = ITBL.TABLE_NAME AND CTE.NOOFROW > 0) -- To check no of record available in table
)
SELECT @tabs = @tabs+ISNULL(','+TABLE_NAME, '')
FROM TABLENAME

DECLARE @cols VARCHAR(MAX) = '';

; WITH CTE AS 
(
 SELECT DISTINCT TA.NAME TABLENAME
      , SUM(PA.ROWS) OVER (PARTITION BY TA.NAME ) NOOFROW
 FROM SYS.TABLES TA
 INNER JOIN SYS.PARTITIONS PA ON PA.OBJECT_ID = TA.OBJECT_ID
 INNER JOIN SYS.SCHEMAS SC ON TA.SCHEMA_ID = SC.SCHEMA_ID
 WHERE TA.IS_MS_SHIPPED = 0 AND PA.INDEX_ID IN (1,0) 
), TABLENAME AS
(
    SELECT ITBL.[TABLE_NAME], ITBL.[COLUMN_NAME]
    FROM INFORMATION_SCHEMA.COLUMNS ITBL
    WHERE ITBL.DATA_TYPE = 'VARCHAR' AND
          ITBL.CHARACTER_MAXIMUM_LENGTH = 8000  
          AND EXISTS(SELECT 1 FROM CTE WHERE CTE.TABLENAME = ITBL.TABLE_NAME AND CTE.NOOFROW > 0) -- To check no of record available in table
)
SELECT @cols = @cols+ISNULL(','+[TABLE_NAME]+'.'+[COLUMN_NAME], '')
FROM TABLENAME

IF LEN(@cols) > 0 AND LEN(@tabs) > 0
BEGIN
    DECLARE @query VARCHAR(MAX) = 'SELECT ' + STUFF(@cols,1,1,'') + ' FROM ' + STUFF(@tabs,1,1, '')

    EXEC sp_sqlexec @query  
END
ELSE
BEGIN
    PRINT 'No Column available with data where it''s datatype is VARCHAR and length is 8000'
END

---

首先打印出

@query

。答案很可能是显而易见的，我做到了。这个查询是正确的。也没有错误。