小编man*_*amz的帖子

这是我的sql(在mysql表中)

select * from(SELECT sample_register.usin,    
                     DATE_FORMAT(sample_register.doc,'%d-%m-%Y') as doc1,    
                     sample_register.location,    
                     sample_register.description,    
                     sample_register.type,    
                     sample_allocation.gamma,    
                     gamma_results.act,    
                     gamma_results.act_sd,    
                     gamma_results.mdl,    
                     gamma_results.bdl,    
                     DATE_FORMAT(count_dt,'%d-%m-%Y') as count_dt    
               FROM sample_register    
               LEFT JOIN sample_allocation    
               ON sample_register.usin=sample_allocation.usin    
               LEFT JOIN gamma_results    
               ON gamma_results.usin = sample_register.usin    
               AND gamma_results.istp='Cs137'    
               WHERE mid(sample_register.usin,3,1)='F'    
               AND sample_register.doc BETWEEN '2015-01-01'    
                                       AND '2015-03-31'    
                                       AND sample_register.category='ter'    
                                       AND sample_allocation.gamma='Y'    
               ORDER BY mid(sample_register.usin,3,1),    
                        sample_register.doc,    
                        sample_register.usin) AS a    
               LEFT JOIN (SELECT sample_register.usin,    
                                 gamma_results.act,    
                                 gamma_results.act_sd,    
                                 gamma_results.mdl,    
                                 gamma_results.bdl    
                          FROM sample_register    
                          LEFT JOIN gamma_results    
                          ON gamma_results.usin = sample_register.usin    
                          AND gamma_results.istp='k40'    
                          WHERE mid(sample_register.usin,3,1)='F'    
                          AND sample_register.doc    
                          BETWEEN '2015-01-01'    
                          AND …

我有3张桌子.表A有两个字段代码和项目.表B有3个字段代码,qty_recd和recd_dt.表C有3个字段Code,qty_sold,sold_dt.我希望以这种方式获得结果:

对于表A中的每个记录,表B中的qty_recd和表C中qty_sold之和的总和.

TABLE-A

code      Item
-----     ------
A1       AMMONIA SOLUTION


TABLE-B

code     qty_recd       recd_dt
-----    --------       -------
A1         5            2013-06-01
A1         8            2013-04-18
A1         3            2013-05-22


TABLE-C

code     qty_sold       sold_dt
-----    --------       -------
A1         1            2013-08-10
A1         4            2013-09-01
A1         2            2013-05-11

我想要这样的结果

code      item            tot_recd       tot_sold
-----    --------         -------       --------
A1     AMMONIA SOLUTION     16             6

我尝试了几种结构,但没有获得所需的输出.请帮忙构造SELECT语句