动态查询游标

Question

我需要为游标编写动态查询以获取表的索引名称。

尝试1：

DECLARE @Cur AS Cursor

EXECUTE SP_EXECUTESQL N'SET @Cur = CURSOR fast_forward for 
                        SELECT IndexColumn = i.name
                        FROM sys.indexes i
                        INNER JOIN sys.tables t ON t.object_id = i.object_id
                        WHERE
                        T.Name = ''' + @TableName + ''''

错误：'+'附近的语法不正确。

尝试2：

 DECLARE @sqlstatement nvarchar(max)

 SET @sqlstatement = 'DECLARE @Cur AS CURSOR fast_forward for 
                 SELECT IndexColumn = i.name
                 FROM sys.indexes i
                 INNER JOIN sys.tables t ON t.object_id = i.object_id
                 WHERE
                 T.Name = ''' + @TableName + ''''
 PRINT(@sqlstatement)
 EXEC sp_executesql @sqlstatement

错误：'fast_forward'附近的语法不正确。

Answer 1

游标声明不正确（丢失@ / AS）

 SET @sqlstatement = 'DECLARE Cur CURSOR fast_forward for 
                 SELECT IndexColumn = i.name
                 FROM sys.indexes i
                 INNER JOIN sys.tables t ON t.object_id = i.object_id
                 WHERE
                 T.Name = ''' + @TableName + ''''

（尝试1不正确，因为光标不在字符串中构建的批处理范围内）

Answer 2

因为游标不在范围内，所以不需要声明。你也可以这样做 -

SET @sqlstatement = 'DECLARE cur_mycursor CURSOR fast_forward for 
                 SELECT IndexColumn = i.name
                 FROM sys.indexes i
                 INNER JOIN sys.tables t ON t.object_id = i.object_id
                 WHERE
                 T.Name = ''' + @TableName + ''''
EXEC(@sqlstatement)

OPEN cur_mycursor

FETCH NEXT FROM cur_mycursor INTO .... blah..blah...