MYSQL - LEFT JOIN Query

 LEFT JOIN Query in mysql is used to join multiple tables which return all the records from the first (left-side) table even no matching records found from the second (right side) table. If it will not find any matches record from the right side table, then returns null.

• We can use MySQL LEFT JOIN Multiple Tables.
• We can use LEFT JOIN with WHERE Clause.
• We can use MySQL LEFT JOIN with Group By Clause.
• We can use MySQL LEFT JOIN with USING Clause.

MYSQL Syntax :

SELECT field_name1, field_name2, ....
FROM table1
LEFT JOIN table2
ON Join_Condition;

MySQL LEFT JOIN – Venn Diagram

MYSQL Query Example :
SELECT s.stud_id,s.stud_name,m.maths,m.science FROM tblstudent s LEFT JOIN tblmarks m on s.stud_id=m.stud_id

 

Explain:

• The tblstudent is the left table and tblmarks is the right table.
• Above LEFT JOIN clause query returns all records of  table tblstudent even no matching records found from table tblmarks with null value.