返回行計數使用動態SQL

Question

我試圖運行下面的動態SQL語句：

@Tbl，@Fld和@LookupValue已全部按表搜索，字段（或列）設爲搜索和列值進行比較。

DECLARE @Sql AS VARCHAR(500) 
SET @Sql = 'SELECT COUNT(*) 
      FROM ' + @Tbl + 
      ' WITH (NOLOCK) 
      WHERE ' + @Fld + ' = ''' + @LookupValue + '''' 

EXEC(@Sql) 

我想將結果存儲到一個變量，所以我可以檢查是否有任何返回的行。該語句位於正在檢查多個表和字段的WHILE構造中。

如果找到了記錄，那麼我想顯示：

SET @Sql = 'SELECT ' + @Fld + 
      ' FROM ' + @Tbl + 
      ' WITH (NOLOCK) 
      WHERE ' + @Fld + ' = ''' + @LookupValue + '''' 

EXEC(@Sql) 

Answer 1

您可以創建臨時表和存儲的計數值。

if object_id('tempdb.#mycount') is null 
create table #mycount (countVal int); 

DECLARE @Sql AS VARCHAR(500) 
SET @Sql = 'INSERT INTO #mycount 
      SELECT COUNT(*) 
      FROM ' + @Tbl + 
      ' WITH (NOLOCK) 
      WHERE ' + @Fld + ' = ''' + @LookupValue + '''' 

EXEC(@Sql) 

select countVal from #mycount 


-- once the temp table usage is done, you can delete it 
drop table #mycount 

Answer 2

是的，你可以將其存儲在一個類型的變量，並使用sp_executesql像

DECLARE @Sql AS NVARCHAR(500); 
DECLARE @cnt INT; 

SET @Sql = 'SELECT @cnt = COUNT(*) 
      FROM ' + @Tbl + 
      ' WITH (NOLOCK) 
      WHERE ' + @Fld + ' = ''' + @LookupValue + ''''; 

EXEC sp_executesql @Sql, N'@var INT OUTPUT', @var OUTPUT; 

SELECT @var;