sql oracle左连接问题 [英] sql oracle left join issue

问题描述

大家好，我有一个sql查询的问题：



i有2个表，我想要table1左连接table2，任务是显示全部table1的行和每个table1的行，我搜索所有table2中的记录，直到第一个匹配的值。



所以

hi guys, i have an issue with sql query:

i have 2 tables, and i want table1 left join table2, mission is to show all table1's rows and for each table1's row, i search records in all table2 until the 1st matched value.

so

results' row number = talbe1's row number

，只需添加table2的第一个匹配值，但在这里我得到

, just add table2's 1st matched value, but here i get

results' row number >talbe1's row number

，任何帮助，plz。*

, any help, plz.*

推荐答案

查看左外连接 [ ^ ]



希望这会对你有所帮助。



干杯

Hi,

Check this Left Outer Join[^]

Hope this will help you.

Cheers

类似于：

Something like:

SELECT * FROM TableA
LEFT OUTER JOIN 
(SELECT relevantField, ROWNUMBER() OVER(PARTITON BY ID ORDER BY RelevantField2 DESC) RN
 FROM TableB) b
ON TableA.Field = TableB.Field
WHERE b.RN = 1

在不知道表格结构的情况下，你必须自己输入正确的字段名称，但想法是将ROWNUMBER添加到第二个子查询中的表允许您仅选择连接产生的第一个记录。

Without knowing the table structure, you have to put in the correct field names yourself, but the idea is that adding a ROWNUMBER to the second table in the subquery allows you to select only the first record resulting from the join.

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