Question

我有两张桌子：

第一表数据（工作流程）：

workflow_id, name, process_id, branch_id, is_parralel , flow_order
80,          AA,      27,       0,         No,          1
81,            ,      27,       0,         Yes,         2
82,          CC,      27,       0,         No,          3 
83,          BB,      27,       116,       No,          1
84,          DD,      27,       117,       No,          1
85,          EE,      27,       116,       No,          2

第二表数据（workflow_parallel_branch）：

id, workflow_id, branch_name
116,  81,         Branch1
117,  81,         Branch2

我想以下面的格式获取数据。我该如何进行此查询？

workflow_id,  name
  80,           AA
  83,           BB
  85,           EE
  84,           DD
  82,           CC

Answer 1

我猜他希望他们按照80,81,82的顺序，其中81被指定的分支116,116,117替换。然后回到原始顺序 - ＆gt; 82

不知道这在mysql中是否有效：

with workflow (workflow_id, name, branch_id) as                 
(values (80, 'AA', 0), (81, NULL, 0), (82, 'CC', 0),            
        (83, 'BB', 116), (84, 'DD', 117), (85, 'EE', 116)),      
     workflow_parallel_branch (id, workflow_id) as              
(values (116, 81), (117, 81)),                                  
     tmp (id, br, orig, name) as                                
(select  coalesce(b.workflow_id, a.workflow_id), a.branch_id,   
         a.workflow_id, a.name                                  
 from   workflow a                                              
 left   join workflow_parallel_branch b on a.branch_id = b.id   
 order  by a.workflow_id, a.branch_id)                          
select orig, name                                               
from   tmp                                                      
where  name is not null                                         
order  by id,br

==＆GT;

ORIG   NAME
  80    AA 
  83    BB 
  85    EE 
  84    DD 
  82    CC

从两个表（父子）mysql查询中获取数据？

1 个答案: