sql - SQL查询我有一个表名student，有两列名称和状态

Question

我有一个表名 student 有两列name和status

CREATE TABLE student
(
  name varchar(30) , status varchar(30) 
);

INSERT INTO student 
(name, status) 
VALUES 
('a','pass'),
('a','fail'),
('a','pass'),
('b','fail'),
('b','fail'),
('b','pass');

查询应显示 3 列

name pass fail
a    2      1
b    1      2

即学生的姓名对应于哪个计数。他们通过的科目和他们未通过的科目数应显示在结果中。

Answer 1

select name,
sum(case when status = 'pass' then 1 else 0 end) as sumPass,
sum(case when status = 'fail' then 1 else 0 end) as sumFail
From student
group by name

和sqlFiddle

Answer 2

您可以简单地在 MYSQL 中使用它：（假设您使用的是 MYSQL，不能移植到 Oracle, SQL Server）

MYSQL 演示

select name,
sum(status = 'pass') as Pass,
sum(status = 'fail') as Fail
From student
group by name
;

| NAME | PASS | FAIL |
----------------------------
|    a |       2 |       1 |
|    b |       1 |       2 |