Question

我们有3列rx, dateTime and tx。一个rx可以有多个tx。

表格是table1

案例1：

如果rx同时具有tx < 8 and tx> 8类型，则选择tx<8的完整行。

案例2：

如果rx只有tx>8，则选择唯一的最新tx。

有人可以帮忙吗？

以下是示例：

注意更高的日期时间值确定最新

rx  tx  date time
1   9   24
1   7   23
1   4   23
1   10  26
2   10  4
2   14  8
2   18  20
2   9   19

预期结果：

rx  tx  datetime
1   7   23
1   4   23
2   18  20

Db是Informix 注意：-no对tx＆lt; 8没有操作，并且没有tx = 8

的数据

Answer 1

让我们准备你给出的测试用例：

[infx1210@tardis tmp]$ dbaccess -e demo test.sql

Database selected.

CREATE TABLE table1 (
        rx                      SMALLINT,
        tx                      SMALLINT,
        date_time       SMALLINT
);
Table created.

INSERT INTO table1 VALUES (1, 9, 24);
1 row(s) inserted.

INSERT INTO table1 VALUES (1, 7, 23);
1 row(s) inserted.

INSERT INTO table1 VALUES (1, 4, 23);
1 row(s) inserted.

INSERT INTO table1 VALUES (1, 10, 26);
1 row(s) inserted.

INSERT INTO table1 VALUES (2, 10, 4);
1 row(s) inserted.

INSERT INTO table1 VALUES (2, 14, 8);
1 row(s) inserted.

INSERT INTO table1 VALUES (2, 18, 20);
1 row(s) inserted.

INSERT INTO table1 VALUES (2, 9, 19);
1 row(s) inserted.

SELECT * FROM table1;

    rx     tx date_time

     1      9        24
     1      7        23
     1      4        23
     1     10        26
     2     10         4
     2     14         8
     2     18        20
     2      9        19

8 row(s) retrieved.

Database closed.

[infx1210@tardis tmp]$

案例1：如果rx同时具有tx < 8 and tx > 8类型，则选择tx < 8的完整行。

SELECT  t1.rx, 
        t1.tx, 
        t1.date_time
FROM    table1 t1
    INNER JOIN (
        SELECT  rx, 
                MAX(tx) AS max_tx, 
                MIN(tx)  AS min_tx 
        FROM    table1 
        GROUP BY 1
    ) t2 ON t1.rx = t2.rx
WHERE   8 BETWEEN t2.min_tx AND t2.max_tx
        AND t1.tx < 8;

案例2 如果rx只有tx > 8，则选择唯一一个最新的tx，因此date_time <更高/ p>

SELECT  t1.rx, 
        t1.tx, 
        t1.date_time
FROM    table1 t1
    INNER JOIN (
        SELECT  rx, 
                MIN(tx) AS min_tx,
                MAX(date_time) AS latest_tx
        FROM    table1 
        GROUP BY 1
    ) t2 ON t1.rx = t2.rx
WHERE   t2.min_tx > 8
        AND t1.date_time = t2.latest_tx;

现在，可以使用UNION语句来组合结果集：

SELECT  t1.rx, 
        t1.tx, 
        t1.date_time
FROM    table1 t1
    INNER JOIN (
        SELECT  rx, 
                MAX(tx) AS max_tx, 
                MIN(tx)  AS min_tx 
        FROM    table1 
        GROUP BY 1
    ) t2 ON t1.rx = t2.rx
WHERE   8 BETWEEN t2.min_tx AND t2.max_tx
        AND t1.tx < 8
UNION
SELECT  t1.rx, 
        t1.tx, 
        t1.date_time
FROM    table1 t1
    INNER JOIN (
        SELECT  rx, 
                MIN(tx) AS min_tx,
                MAX(date_time) AS latest_tx
        FROM    table1 
        GROUP BY 1
    ) t2 ON t1.rx = t2.rx
WHERE   t2.min_tx > 8
        AND t1.date_time = t2.latest_tx;

为Informix DB准备SQL查询

案例1：

案例2：

1 个答案: