There are two tables in my Oracle database.
First table is (customers)-
customer_id Customer_name Customer_age Customer_address salary
103 Giriraj Rathi 22 Kolkata 12000
100 Subir Adhikari 22 Bolpur 10000
101 Rakesh Chatterjee 21 Tarkeshwar 8000
102 Jayanta Patra 20 Tarkeshwar 9000
104 Abhi Karmakar 22 Burdwan 8000
105 Mainak Manna 21 Burdwan 9000
106 Subho Gupta 20 Kolkata 10000
107 Aritra Das 23 Kolkata 7000
108 Pradip Paul 22 Kolkata 5000
109 Sourav Banerjee 22 Bolpur 9000
Second table is (Orders):
Order_id Order_date customer_id amount
200 12-03-13 100 1100
201 09-05-13 101 1400
202 07-04-12 103 2500
204 29-05-13 104 2400
203 09-02-13 105 9000
205 18-06-13 106 2100
206 09-07-13 107 1600
207 18-05-13 108 2900
209 18-04-13 109 2400
Now I wanted to join both the tables. So I used the query:
select customer_id,
customer_name,
customer_address,
order_id,order_date,
amount
from customers,
orders
where customers.customer_id=orders.customer_id;
I Googled about the error and found this happens when there is ambiguity in the SQL code itself, but in this case I see nothing.
It is always a good idea to add the table name/alias to the column like this
select c.customer_id,
c.customer_name,
c.customer_address,
o.order_id,
o.order_date,
o.amount
from customers c
inner join orders o on c.customer_id = o.customer_id
If you don't then the DB don't know which column to take and both tables have a column named customer_id.