sql - PostgreSQL 9.3 : Pivot table query

Question

我想显示给定下表的数据透视表(交叉表)。

表:员工

CREATE TABLE Employee
(
Employee_Number varchar(10),
Employee_Role varchar(50),
Group_Name varchar(10)
);

插入:

INSERT INTO Employee VALUES('EMP101','C# Developer','Group_1'),
                           ('EMP102','ASP Developer','Group_1'),
                           ('EMP103','SQL Developer','Group_2'),
                           ('EMP104','PLSQL Developer','Group_2'),
                           ('EMP101','Java Developer',''),
                           ('EMP102','Web Developer','');

现在我想显示上述数据的数据透视表，如下所示:

预期结果:

Employee_Number     TotalRoles      TotalGroups       Available     Others     Group_1     Group_2
---------------------------------------------------------------------------------------------------
   EMP101               2                2                1           1           1           0
   EMP102               2                2                1           1           1           0
   EMP103               1                2                1           0           0           1 
   EMP104               1                2                1           0           0           1

说明:我想显示每个员工拥有的Employee_Number，TotalRoles，TotalGroups 显示给所有员工，Available 显示可用的员工在多少个组中，Others 必须显示该员工在其他组中也有空group_name 尚未分配，最后 Group_Names 必须以数据透视格式显示。

Answer 1

SELECT * FROM crosstab(
      $$SELECT grp.*, e.group_name
             , CASE WHEN e.employee_number IS NULL THEN 0 ELSE 1 END AS val
        FROM  (
           SELECT employee_number
                , count(employee_role)::int            AS total_roles
                , (SELECT count(DISTINCT group_name)::int
                   FROM   employee
                   WHERE  group_name <> '')            AS total_groups
                , count(group_name <> '' OR NULL)::int AS available
                , count(group_name =  '' OR NULL)::int AS others
           FROM   employee
           GROUP  BY 1
           ) grp
        LEFT   JOIN employee e ON e.employee_number = grp.employee_number
                              AND e.group_name <> ''
        ORDER  BY grp.employee_number, e.group_name$$
     ,$$VALUES ('Group_1'::text), ('Group_2')$$
   ) AS ct (employee_number text
          , total_roles  int
          , total_groups int
          , available    int
          , others       int
          , "Group_1"    int
          , "Group_2"    int);

SQL Fiddle演示基本查询，但不演示 sqlfiddle.com 上未安装的交叉表步骤

交叉表的基础知识:

• PostgreSQL Crosstab Query

此交叉表的特殊之处:所有“额外”列。这些列位于中间，在“行名”之后但在“类别”和“值”之前:

• Pivot on Multiple Columns using Tablefunc

再一次，如果您有一组动态组，则需要动态构建此语句并在第二次调用中执行它:

• Selecting multiple max() values using a single SQL statement