Question

以下更新查询有什么问题？它给出了语法错误，错误信息如下：

Msg 102，Level 15，State 1，Line 1
'a'附近的语法不正确。

代码：

UPDATE D_date a 
SET d_date_key = b.d_date_key,  
    full_date = b.full_date,    
    day_of_week = b.day_of_week,    
    day_of_week_display = b.day_of_week_display,    
    fiscal_day_number = b.fiscal_day_number 
FROM   
    dbo.[2017 Calendar update] b
WHERE  
    a.d_date_key = b.d_date_key;

Answer 1

您没有在UPDATE子句中为要更新的表添加别名，而是FROM中的别名。正确的语法是：

UPDATE a
SET d_date_key =b.d_date_key ,  
    full_date=b.full_date,  
    day_of_week=b.day_of_week,  
    day_of_week_display=b.day_of_week_display,  
    fiscal_day_number=b.fiscal_day_number   
FROM D_date a
     JOIN dbo.[2017 Calendar update] b ON a.d_date_key = b.d_date_key;

然而，使用升序字母字符（a，b，c，d）或类似想法（如{{1} }}，T1，T2等等，因为它们对每个人都毫无意义。使用适当的别名。例如T3的{{1}}和D的{{1}}。

Answer 2

显然，SQL Server中update语句的update部分不允许使用别名。而只需使用表名：

UPDATE D_date 
    SET d_date_key = b.d_date_key ,  
        full_date = b.full_date,  
        day_of_week = b.day_of_week,  
        day_of_week_display = b.day_of_week_display,  
        fiscal_day_number = b.fiscal_day_number   
    FROM  dbo.[2017 Calendar update] b
    WHERE D_date.d_date_key = b.d_date_key;

或者使用明确的JOIN和合理的别名：

UPDATE D_date 
    SET d_date_key = cu.d_date_key ,  
        full_date = cu.full_date,  
        day_of_week = cu.day_of_week,  
        day_of_week_display = cu.day_of_week_display,  
        fiscal_day_number = cu.fiscal_day_number   
    FROM D_date d JOIN
         dbo.[2017 Calendar update] cu
         ON d.d_date_key = cu.d_date_key;

这个SQL Server查询有什么问题

2 个答案: