内部联接返回大量重复项 [英] Inner join returning large numbers of duplicates

问题描述

我正在使用以下查询将两个表连接在一起:

I am using the following query to join two tables together:

SELECT SDA.smachIPAddress,
DPP.ScanName,
DPP.pspplMSSeverity,
DPP.PatchMissing,
DPP.ScanDate
FROM patchtest_withsev DPP
INNER JOIN patchtest_withip SDA
ON DPP.ScanName =SDA.ScanName

并接收2351行数据

当我查询patchtest_withsev表的所有记录时，它仅返回99，而patchtest_withip表仅返回99.

When I query the patchtest_withsev table for all records it only returns 99 and the patchtest_withip table only returns 99.

谁能看到为什么这个查询产生如此大的不匹配?

Can anyone see why this query is producing such a large mismatch?

推荐答案

似乎两个表都有几行，且每行具有相同的ScanName值.

It seems that both table have several rows with same values of ScanName.

例如:

table1:
f1 | f2
 1 | a
 1 | b
 2 | c
 2 | c

table2:
f1 | f2
 1 | a
 1 | b
 2 | c

table1 INNER JOIN table2 ON table1.f1 = table2.f1给出:

table1 INNER JOIN table2 ON table1.f1 = table2.f1 gives:

table1.f1 | table1.f2 | table2.f1 | table2.f2
        1 |         a |         1 |         a
        1 |         a |         1 |         b
        1 |         b |         1 |         a
        1 |         b |         1 |         b
        2 |         c |         2 |         c
        2 |         c |         2 |         c

为避免结果中出现完全重复的行，请尝试使用DISTINCT.

To avoid completely duplicate rows in result try using DISTINCT.

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