Question

I am searching for a real scenario problem that I faced last night while joining two tables with foreign keys. Actually I want to get all values from second table on behalf of foreign key.

Here are my two tables let suppose:

table1 (id_user_history(PK),id_user(FK), order_no, p_quantity)
table2 (id_shoping_cart(PK), id_user(FK),order_id, prod_quantity)

Now I want to get all values from table2 by joining these tables with table1(id_user(Fk)) and table2( id_user(FK))

Answer 1

SELECT  *
FROM    table2 t2
LEFT JOIN
        table1 t1
on      t1.id_user = t2.id_user

all records from table 2 and only those record which match on table 1.

SQL is mainly set logic. Here’s a link which helps visualize.
http://www.codinghorror.com/blog/2007/10/a-visual-explanation-of-sql-joins.html