Question

我有两个案例表。 tbl_emp是主表，说： -

 ----------------------------------------------------------
   tbl_emp
 ----------------------------------------------------------
    emp_id            emp_name
     1                  Peter
     2                  Matt
     3                  Jacob
 ----------------------------------------------------------

并且详细信息表中包含员工的家庭详细信息.......

 -----------------------------------------------------------------
  tbl_family
 ----------------------------------------------------------------
   family_id         emp_id        relation       name       age
 -----------------------------------------------------------------
     1                 1            WIFE          Susan       32
     2                 1            SON           Jack        3
     3                 2            DAUGHTER      Hannah      4
     4                 2            WIFE          Leah        29
     5                 1            WIFE          Anna        38
     6                 3            MOTHER        Loran       73
     7                 2            MOTHER        Sofia       81
 ------------------------------------------------------------------

我想要一个查询来了解所有员工在tbl_family中有一个特定的“关系”条目以及谁不具备。例如，我管理了对具有WIFE条目的雇员的以下查询

 select * from tbl_emp, tbl_family where
 tbl_emp.emp_id = tbl_family.emp_id and
 tbl_family.relation = 'WIFE'

此查询正确返回Peter和Matt。但我需要查询三个问题。首先。给我在tbl_family没有WIFE条目的员工。即输出应该是

  ---------------------------------------
    emp_id        emp_name
  ---------------------------------------
      3            Jacob
  ---------------------------------------

seconldy，为其提供的数据集记录两个WIFE条目（或任何其他关系）

 -----------------------------------------
   emp_id            emp_name
 -----------------------------------------
     1                Peter
 -----------------------------------------

最后，所有拥有WIFE和MOTHER条目的员工。这个查询将返回

 -----------------------------------------
   emp_id            emp_name
 -----------------------------------------
     2               Matt
 -----------------------------------------

我已编辑了所有结果输出的问题。感谢。

Answer 1

第一点：

 --wihout wife
 select tbl_emp.* 
 from tbl_emp  
 left join tbl_family 
 on 
   tbl_emp.emp_id = tbl_family.emp_id and tbl_family.relation = 'WIFE'
 where tbl_family.emp_id IS NULL;

第二点：

 --having any relation at least twice
 select tbl_emp.id, tbl_emp.name, tbl_family.relation
 from tbl_emp  
 left join tbl_family 
 on 
   tbl_emp.emp_id = tbl_family.emp_id 
 group by tbl_emp.id, tbl_emp.name, tbl_family.relation
 having count(tbl_family.emp_id) > 1;

第三点：

 --having WIFE, SON AND DAUGHTER.
 select tbl_emp.id, tbl_emp.name 
 from tbl_emp  
 left join tbl_family 
 on 
   tbl_emp.emp_id = tbl_family.emp_id and (
     tbl_family.relation = 'WIFE' or 
     tbl_family.relation = 'SON' or 
     tbl_family.relation = 'DAUGHTER'
     )
 group by tbl_emp.id, tbl_emp.name
 having count(distinct tbl_family.relation) >= 3;

Answer 2

第三点：

SELECT tbl_emp.*
  FROM tbl_emp
   INNER JOIN tbl_family tf1
      ON tbl_emp.emp_id = tf1.emp_id AND tf1.relation = 'WIFE'
   INNER JOIN tbl_family tf2
      ON tbl_emp.emp_id = tf2.emp_id AND tf2.relation = 'MOTHER';

Answer 3

你应该玩tbl_family.relation = 'WIFE'

您可以使用例如（tbl_family.relation = 'WIFE' OR tbl_family.relation = 'MOTHER' OR tbl_family.relation = 'DAUGHTER'）

此外，您可以使用OUTER JOIN查找没有家人的人

从详细信息表中具有特定记录的主表返回记录

3 个答案: