SQL Joins

SQL JOINS EXAMPLES:


Below are two tables #A and #B, There are A_id and B_id columns in the tables respectively. We have inserted a few values in both the tables. Please note that 50 is the common value in both tables.



INNER JOIN:


Matching records from both the tables will be the output:





LEFT OUTER JOIN:


All records from LEFT table and Matching records from Right table. NULL where the condition doesn't match:







RIGHT OUTER JOIN:


All records from RIGHT table and Matching records from LEFT table. NULL where the condition doesn't match:





FULL OUTER JOIN:


All records from both tables, Matching records from both tables and NULL wherever no match.





CROSS JOIN:


Cartesian product of both tables: 4*4 = 16 records in this case. Please note that there will be no condition in this case.





UNION:


Duplicate matching records entries are removed. All other records are union.







UNION ALL:


Duplicate entries will be there in this case.