Question

我有4张桌子

Table1 (employee)
id          name
--------------------
1           a
2           b

Table2 (appointment)
id    table1id    table3id    table4id   sdate    edate     typeid
-----------------------------------------------------------------------------------
1       1              1          1      1/1/09    NULL       100
2       2              2          1      1/1/09    NULL       101


Table3 (title)
id      name
---------------
1       worker1
2       worker2
3       Assistant
4       Manager

Table4 (Department names)
id      name
-------------------
1       Logistics
2       ABC
3       XYZ

Type
id       name
----------------
100      w (primary)
101      e (secondary)
102      r (other-primary)
103      t (.....)
104      y (....)

为避免重复我将查询编写为

Select id, name, title, dept
FROM table1 a
INNER JOIN table2 b ON a.id = b.table1id
INNER JOIN table3 c ON b.table3id = c.id
INNER JOIN table4 d ON d.id = b.table4id
WHERE typeid =
        (
           SELECT min(type_id) /* i want primary type appointments */
           FROM table2
           WHERE sdate < getdate() and (edate > getdate() or edate IS NULL)
           AND sdate = (select max(sdate) from table2 where table1id = a.id)
           AND typeid in (100, 102)
        )
AND b.sdate < getdate() and (b.edate > getdate() or b.edate IS NULL)
AND b.sdate = (select max(sdate) from table2 where table1id = a.id)

/* last two i have to repeat again to remove dupes */

有没有办法可以减少使用相同的条件两次并查询它只指定一次或任何其他更好的方式？ AND typeid in（100,102）

Answer 1

这样的事情是否会有所改进，在联接中使用子查询来获取您想要的数字？

Select id, name, title, dept
FROM table1 a
INNER JOIN table2 b ON a.id = b.table1id
INNER JOIN table3 c ON b.table3id = c.id
INNER JOIN table4 d ON d.id = b.table4id
INNER JOIN (select max(sdate) from table2 group by table1id) new1 ON new1.table1id = a.id
WHERE typeid =
    (
       SELECT min(type_id) /* i want primary type appointments */
       FROM table2
       WHERE sdate < getdate() and (edate > getdate() or edate IS NULL)
       AND sdate = (select max(sdate) from table2 where table1id = a.id)
       AND typeid in (100, 102)
    )
AND b.sdate < getdate() and (b.edate > getdate() or b.edate IS NULL)
AND b.sdate = new1.sdate

您也可以尝试查看GROUP BY的HAVING子句。我想你可以做类似的事情：

Select id, name, title, dept
FROM table1 a
INNER JOIN table2 b ON a.id = b.table1id
INNER JOIN table3 c ON b.table3id = c.id
INNER JOIN table4 d ON d.id = b.table4id
WHERE b.sdate < getdate() and (b.edate > getdate() or b.edate IS NULL)
AND typeid in (100, 102)
GROUP BY id, name, title, dept
HAVING b.sdate = max(sdate)
  AND typeid = min(type_id)

但是上面的内容可能会拉出整个列表的最小值和最大值，而不是每个a.id.我忘记了你是否可以使用max中的分区来指定最大值，或者我是否考虑使用Oracle。如果没有，您可以始终使用为每个a.id获取最佳条目的子查询。

Answer 2

我使用了相同的查询并且工作正常，我没有找到任何其他方法来优化它

如何优化或删除后续查询的冗余

2 个答案: