[英]MySQL: How to join two tables with some rows that does not match
I have two MySQL Tables: 我有两个MySQL表:
table1: 表格1:
myTime|foo
----------
00:00 |8
----------
00:10 |6
----------
00:20 |1
----------
00:30 |5
----------
00:40 |3
----------
00:50 |4
----------
table2: 表2:
myTime|bar
----------
00:00 |6
----------
00:10 |10
----------
00:50 |5
----------
I want to get this result: 我想得到这个结果:
myTime|foo|bar
--------------
00:00 |8 |6
-------------
00:10 |6 |10
-------------
00:20 |1 |
-------------
00:30 |5 |
-------------
00:40 |3 |
-------------
00:50 |4 |5
-------------
Despite there are no entries for time = 0:20 - 0:40 in table 2 this rows should not be skiped in the result. 尽管表2中没有时间= 0:20-0:40的条目,但不应在结果中跳过这些行。
This is precisely what left join
s are for: 这正是left join
的作用:
SELECT table1.mytime, foo, bar
FROM table1
LEFT JOIN table2 ON table1.mytime = table2.mytime
您可以使用myTime字段左加入。
SELECT table1.mytime,
table1.foo,
table2.mytime,
table2.bar
FROM table1
LEFT JOIN table2 ON table1.mytime = table2.mytime;
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