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mysql – 在ORDER BY之后计算记录

发布时间:2020-12-11 23:33:57 所属栏目:MySql教程 来源:网络整理
导读:我有代码来计算记录,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.问题是我想首先ORDER BY SN并在之后分配cnt? 我的代码是: 表 create table rot ( code int(10) primary key,PN varchar(10) not null,SN varchar(10) not null,LocID int

我有代码来计算记录,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.问题是我想首先ORDER BY SN并在之后分配cnt?

我的代码是:

 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,'T1SN2','5');
    insert into rot values (9,'A1SN2','1');
    insert into rot values (10,'J2SN2','3');
    insert into rot values (11,'J2SN3','4');
    insert into rot values (12,'A1SN3','3');
    insert into rot values (13,'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,代码必须以SELECT开头. 最佳答案 根据我的理解,并根据我对你的问题所作的评论,我将引用下一篇:

In the Results table and the logic of the query you have made,the
cnt column keep a counter of the number of codes that are greater or equal compared to the code value of the row. In other words,and
for example,code 2 is lower or equal than codes 2,3,4 and 5,so you
store a 4 on the cnt column. But,in the Desired Results this
has lost all sense,since you only save the position of the current
ordering on the cnt column.

假设您只需要在cnt列上使用SN的订单位置,您可以尝试下一个不依赖于MySQL 8.0并且不使用用户变量的解决方案:

SELECT rot.*,loc.*,( SELECT COUNT(*)
         FROM rot AS rot1
         INNER JOIN loc AS loc1 ON loc1.code1 = rot1.code
         WHERE rot1.SN <= rot.SN ) AS cnt
FROM
    rot
INNER JOIN
    loc ON loc.code1 = rot.code
ORDER BY
    rot.SN

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