How to obtain the unique matching data when querying two or more data tables in the left-join query of MySQL

When querying two or more data tables in the left join query of MySQL, how do you obtain the unique matched data? & nbsp; when using the left join query, more than two data tables are involved, although data can be queried, there are multiple matching results. it is like using a common association query. thank you for your advice ., Select * fromaleftj MySQL how to obtain the unique matched data when querying two or more data tables in the left join query
Experts:
When I use the left join query, more than two data tables are involved. although the data can be queried, multiple matching results are displayed, it is like using a common association query. thank you for your advice.

------ Solution --------------------
Select *
From a left join B on a. id = B. id
Left c on a. id = c. id
------ Solution --------------------
You need to add a where condition next to it.
------ Solution --------------------
Left join ON condition
And where
------ Solution --------------------
ID data type must match