参数化查询不限制在MSSQL服务器

Question

我有一个项目正在工作，我一直在测试我的查询，看看他们是如何工作的，但问题是当我传递一个参数到查询它不是限制它的参数我通过。

下面是查询语法：

SELECT C.*, 
      F.Bank_VNO, 
      F.sname 
    FROM customer C 
      LEFT JOIN fssign F 
        ON c.cust_no = f.cust_no 
        AND F.cust_no = '100055' 
      LEFT JOIN (SELECT Min(ac_no) ac_no 
         FROM loans 
         WHERE full_paid = '0' 
         GROUP BY ac_no) AS l 
        ON c.cust_no = l.ac_no 
        AND cust_type = 'BUS' 

Answer 1

我认为这不是很清楚你的意思，但可能是你应该删除GROUP BY：

SELECT C.* 
     ,F.Bank_VNO 
     ,F.sname 
    FROM customer C 
    LEFT JOIN fssign F ON c.cust_no = f.cust_no 
       AND F.cust_no = '100055' 
    LEFT JOIN (SELECT MIN(ac_no) ac_no 
       FROM loans 
       WHERE full_paid = '0' 
/*    GROUP BY ac_no */ 
     ) AS l ON c.cust_no = l.ac_no 
     AND cust_type = 'BUS' 

可能是你想要的查询要写的是：

SELECT C.* 
     ,F.Bank_VNO 
     ,F.sname 
FROM customer C 
INNER JOIN fssign F ON c.cust_no = f.cust_no      
INNER JOIN (SELECT MIN(ac_no) ac_no 
      FROM loans 
      WHERE full_paid = '0' 
      ) AS l ON c.cust_no = l.ac_no 
WHERE C.cust_type = 'BUS' 
AND F.cust_no = '100055' 

Answer 2

Left Join不会过滤记录。它将带来左表中的所有记录，除非您将过滤器置于Where子句中。

我想你只想在cust_type = 'BUS'的记录。将过滤器移至Where子句。假设cust_type列是从customer表

SELECT C.*, 
      F.Bank_VNO, 
      F.sname 
    FROM customer C 
      LEFT JOIN fssign F 
        ON c.cust_no = f.cust_no 
        AND F.cust_no = '100055' 
      LEFT JOIN (SELECT Min(ac_no) ac_no 
         FROM loans 
         WHERE full_paid = '0' 
         GROUP BY ac_no) AS l -- This query does not make more sense 
        ON c.cust_no = l.ac_no 
Where C.cust_type = 'BUS'