MySQL使用左连接计算查询的行数

Question

我有一个如下所示的查询:

 Select x.date, x.id, x.phone,
    x.product, xy.policy,xy.date 
 from (y left join z 
            on y.customer_id=z.customer_id)
    left join x 
       on x.id=z.id 
    left join xy 
       on xy.id=x.id 
 where x.date > '2000-01-01'  
    and y.detail =foo 
    and xy.policy like 'foo_____'  
    and xy.policy_type = foo;

如何计算返回的行数？

我尝试使用 SQL_CALC_FOUND_ROWS，但无法完全适应此查询。

任何帮助将不胜感激。

谢谢，斯特凡。

Answer 1

最简单的就是添加一个子查询...

 Select x.date, x.id, x.phone,
    x.product, xy.policy,xy.date,
    (Select Count(*) 
     From (y left join z on y.customer_id=z.customer_id)
        left join x on x.id=z.id 
        left join xy  on xy.id=x.id 
     where x.date > '2000-01-01'  
       and y.detail =foo 
       and xy.policy like 'foo_____'  
       and xy.policy_type = foo) RecordCount  
 from (y left join z 
            on y.customer_id=z.customer_id)
    left join x 
       on x.id=z.id 
    left join xy 
       on xy.id=x.id 
 where x.date > '2000-01-01'  
    and y.detail =foo 
    and xy.policy like 'foo_____'  
    and xy.policy_type = foo;

如果您想要的只是计数，那么:

 Select Count(*) 
 From (y left join z on y.customer_id=z.customer_id)
    left join x on x.id=z.id 
    left join xy  on xy.id=x.id 
 where x.date > '2000-01-01'  
   and y.detail =foo 
   and xy.policy like 'foo_____'  
   and xy.policy_type = foo