Question

我有用于计数记录的代码，但无法在其之前添加订单。

两个表联接在一起，我添加了代码以对记录进行计数。问题是我要先按SN订购，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');

验证码：

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 |
+------+----+-------+-------+-------+--------+------+-----+

所需结果

+------+----+-------+-------+-------+--------+------+-----+
| 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 |
+------+----+-------+-------+-------+--------+------+-----+

我只是想知道将ORDER BY放在哪里？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

如果使用MySQL 8.0，则可以使用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 |
+-------+-----+--------+--------+--------+---------+-------+-----+

Answer 2

尝试一下：

SELECT * FROM (
    SELECT *
    FROM rot
    JOIN loc ON rot.code = loc.code1
    JOIN (
        SELECT t1.code3, count(*) cnt
        FROM (
            SELECT distinct code as code3
            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.code3 <= t2.code group by t1.code3
    ) tt ON rot.code = tt.code3
)X
ORDER BY X.cnt ASC;

Answer 3

按照上面给出的详细信息，您可以使用以下查询获得所需的结果：

SELECT code, PN,SN,LocID,code1,LocVar ,code, @row := @row + 1 AS cnt FROM (
SELECT  code, PN,SN,LocID,code1,LocVar
FROM rot 
JOIN loc 
ON code=code1
ORDER BY SN) tab, (SELECT @row := 0) r;

所需结果：

+------+----+-------+-------+-------+--------+------+------+
| 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 |
+------+----+-------+-------+-------+--------+------+------+

希望您希望通过查询实现这一目标。请检查并享受:)！

Answer 4

根据我的理解，并根据我对您的问题所作的评论，我将在下一次引用：

在结果表和您所做的查询的逻辑中， cnt 列保留与该行的代码值相比更大或相等的代码数的计数器。换句话说，和例如，代码2低于或等于代码2、3、4和5，因此您在 cnt 列上存储4。但是，在所需结果中，已经失去了所有意义，因为您只保存了当前位置在 cnt 列上排序。

假设您只需要 cnt 列上的 SN 的订单头寸，则可以尝试不依赖于MySQL 8.0并且不使用用户身份的下一个解决方案-变量：

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

Answer 5

SELECT code, PN, SN, LocID, code1, LocVar, code, @rownum:=@rownum + 1 as cnt FROM rot
JOIN loc ON rot.code = loc.code1
JOIN (
    SELECT distinct code
                FROM rot ts2
            JOIN loc tx2 ON ts2.code = tx2.code1

    ) t2 on t1.code <= t2.code 
    group by loc.code1 
    order by rot.SN;

这就是您想要的吗？

mysql-在ORDER BY之后计数记录

5 个答案: