![]() The salesman_id column is null-able, meaning that not all orders have a sales employee who is in charge of the orders. It has the salesman_id column that references to the employee_id column in the employees table. The orders table stores the sales order header data. See the following orders and employees tables in the sample database: In other words, a left join returns all rows from the left table and matching rows from the right table. In case a row in the T1 table does not have any matching row in the T2 table, the query combines column values from the row in the T1 table with a NULL value for each column in the right table that appears in the SELECT clause. If a pair of rows from both T1 and T2 tables satisfy the join predicate, the query combines column values from rows in both tables and includes this row in the result set. The query compares each row in the T1 table with rows in the T2 table. In this query, T1 is the left table and T2 is the right table. The difference is that, for each selected row on the left side as LEFT OUTER JOIN or on the right. Code language: SQL (Structured Query Language) ( sql ) The outer join creates the same results set as the inner join. ![]()
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