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SQL joins are used to retrieve data from multiple tables. A SQL JOIN is performed whenever two or more tables are listed in a SQL statement.
SIX different types SQL joins :
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SQL INNER JOIN : It returns only Matching rows from Both Tables
- SYNTAX : SELECT columns FROM table1 INNER JOIN table2 ON table1.column = table2.column;
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SQL OUTER JOIN : Returns all rows from the left table and matching rows from the right table.
- SYNTAX : SELECT columns FROM table1 LEFT JOIN table2 ON table1.column = table2.column;
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SQL RIGHT OUTER JOIN : Returns all rows from the Right Table and matching rows from the left table.
- SYNTAX : SELECT columns FROM table1 RIGHT JOIN table2 ON table1.column = table2.column;
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SQL FULL OUTER JOIN: Returns all rows from the both tables, with NULL values in columns where there is no match.
- SYNTAX : SELECT columns FROM table1 FULL OUTER JOIN table2 ON table1.column = table2.column;
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SQL SELF JOIN : A self join is a regular join, but the table is joined with itself.
- SYNTAX : SELECT column_name(s) FROM table1 T1, table1 T2 ON T1.column = T2.column;
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SQL CROSS JOIN : The CROSS JOIN returns all records from both tables where it perform M x N action. Also called MxN join. It returns cartesian prodcut.
- SYNTAX : SELECT column_name(s) FROM table1 CROSS JOIN table2;