Mysql left Join Where on

　　

Select T1.id,t2.id
from T1
Left JOIN T2 on t1.id = T2.id and t1.id>1 and t2.id<>3
In the left join of MySQL the condition is placed behind and is different in the back of the Where;

1. On the back only for the T2 table filter, so the above t1.id>1 will not work, remember, remember;

2. Where the end result has an effect, so if the t2.id<>3 is placed behind the on and the where behind will return different results;

For example, the following script will return some data more than script two.

SELECT * FROM Test2
Left join test1 on test2.id = Test1.id and test1.id<>3
where Test2.id <>6;
SELECT * FROM Test2
Left join test1 on test2.id = test1.id
where Test2.id <>6 and test1.id<>3;

Mysql left Join Where on