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Currently I am doing this query:
select a.x, b.x, c.x
from number as a, customer as b, numbergroup as c
where a.b = b.b and a.c = c.c and c.b = b.b
However, I want to retrieve records from table "a" even if "a.c = null", which is not retrieved due to the join between "a" and "c".
I have found information about left join but I don't know how to do it when the query involves more than two tables like in this case.
635
Sometimes you need to LEFT JOIN more than two tables to get the data required for specific analyses. Fortunately, the LEFT JOIN keyword can be used with multiple tables in SQL.
Syntax For Left Join:SELECT column names FROM table1 LEFT JOIN table2 ON table1. matching_column = table2. matching_column; Note: For example, if you have a left table with 10 rows, you are guaranteed to have at least 10 rows after applying join operation on two tables.
select a.x, b.x, c.x
from number as a
left join customer as b on a.b = b.b
left join numbergroup as c on a.c = c.c and c.b = b.b
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