mysql - 计算 ORDER BY 之后的记录

Question

我有计算记录的代码，但无法在它之前添加订单。

连接了两个表，我添加了代码来计算记录。问题是我想先 ORDER BY SN 然后再分配 cnt？

我的代码是:

表格

 create table rot (
            code int(10) primary key,
            PN varchar(10) not null,
        SN varchar(10) not null,
            LocID int(10) not null);

    insert into rot values (1,'T1','T1SN1','1');
    insert into rot values (2,'A1','A1SN1','2');
    insert into rot values (3,'J1','J1SN1','3');
    insert into rot values (4,'A2','A2SN1','1');
    insert into rot values (5,'J2','J2SN1','2');
    insert into rot values (6,'A3','A3SN1','3');
    insert into rot values (7,'J3','J3SN1','4');
    insert into rot values (8,'T1','T1SN2','5');
    insert into rot values (9,'A1','A1SN2','1');
    insert into rot values (10,'J2','J2SN2','3');
    insert into rot values (11,'J2','J2SN3','4');
    insert into rot values (12,'A1','A1SN3','3');
    insert into rot values (13,'J2','J2SN4','5');

    create table loc(
        code1 int(10) primary key,
        LocVar varchar(10) not null);

    insert into loc values (1,'AAA');
    insert into loc values (2,'BBB');
    insert into loc values (3,'CCC');
    insert into loc values (4,'DDD');
    insert into loc values (5,'EEE');

Cnt代码:

SELECT * FROM rot
JOIN loc ON rot.code = loc.code1

JOIN (
            SELECT t1.code, count(*) cnt FROM (
                SELECT distinct code
                FROM rot ts1 
            JOIN loc tx1 ON ts1.code = tx1.code1 

) t1 
JOIN (
    SELECT distinct code
                FROM rot ts2
            JOIN loc tx2 ON ts2.code = tx2.code1

    ) t2 on t1.code <= t2.code 
    group by t1.code 

) tt ON rot.code = tt.code

结果:

+------+----+-------+-------+-------+--------+------+-----+
| code | PN | SN    | LocID | code1 | LocVar | code | cnt |
+------+----+-------+-------+-------+--------+------+-----+
|    2 | A1 | A1SN1 |     2 |     2 | BBB    |    2 |   4 |
|    4 | A2 | A2SN1 |     1 |     4 | DDD    |    4 |   2 |
|    3 | J1 | J1SN1 |     3 |     3 | CCC    |    3 |   3 |
|    5 | J2 | J2SN1 |     2 |     5 | EEE    |    5 |   1 |
|    1 | T1 | T1SN1 |     1 |     1 | AAA    |    1 |   5 |
+------+----+-------+-------+-------+--------+------+-----+

期望的结果

+------+----+-------+-------+-------+--------+------+-----+
| code | PN | SN    | LocID | code1 | LocVar | code | cnt |
+------+----+-------+-------+-------+--------+------+-----+
|    2 | A1 | A1SN1 |     2 |     2 | BBB    |    2 |   1 |
|    4 | A2 | A2SN1 |     1 |     4 | DDD    |    4 |   2 |
|    3 | J1 | J1SN1 |     3 |     3 | CCC    |    3 |   3 |
|    5 | J2 | J2SN1 |     2 |     5 | EEE    |    5 |   4 |
|    1 | T1 | T1SN1 |     1 |     1 | AAA    |    1 |   5 |
+------+----+-------+-------+-------+--------+------+-----+

我只是想知道在哪里放置 ORDER BY？在我的代码中，我无法分配变量并且代码必须以 SELECT 开头。

Answer 1

如果是 MySQL 8.0，你可以使用 ROW_NUMBER :

SELECT *, rot.code, ROW_NUMBER() OVER(ORDER BY SN) AS cnt
FROM rot
JOIN loc ON rot.code = loc.code1
ORDER BY SN;

db<>fiddle demo

+-------+-----+--------+--------+--------+---------+-------+-----+
| code  | PN  |  SN    | LocID  | code1  | LocVar  | code  | cnt |
+-------+-----+--------+--------+--------+---------+-------+-----+
|    2  | A1  | A1SN1  |     2  |     2  | BBB     |    2  |   1 |
|    4  | A2  | A2SN1  |     1  |     4  | DDD     |    4  |   2 |
|    3  | J1  | J1SN1  |     3  |     3  | CCC     |    3  |   3 |
|    5  | J2  | J2SN1  |     2  |     5  | EEE     |    5  |   4 |
|    1  | T1  | T1SN1  |     1  |     1  | AAA     |    1  |   5 |
+-------+-----+--------+--------+--------+---------+-------+-----+