OUTER JOIN

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An outer join is similar to equijoin but it gets also the non-matched rows from the table. It is categorized in Left Outer Join, Right Outer Join and Full Outer Join by Oracle 9i ANSI/ISO 1999 standard.

Left Outer Join

Left Outer Join returns all rows from the left (first) table specified in the ON condition and only those rows from the right (second) table where the join condition is met.

Syntax

  1. SELECT columns  
  2. FROM table1  
  3. LEFT [OUTER] JOIN table2  
  4. ON table1.column = table2.column;   

Image representation of left outer join

Oracle Left Outer Join

Example

In this example, we are performing left outer join on the already created tables ?suppliers? and ?order1?.

The following example would return all records from table ?suppliers? and only those records from table ?order1? where the join fields are equal.

Execute this query

  1. SELECT suppliers.supplier_id, suppliers.supplier_name, order1.order_number  
  2. FROM suppliers  
  3. LEFT OUTER JOIN order1  
  4. ON suppliers.supplier_id = order1.supplier_id;  

Output

Oracle Left Outer Join 2

Right Outer Join

The Right Outer Join returns all rows from the right-hand table specified in the ON condition and only those rows from the other table where the join condition is met.

Syntax

  1. SELECT columns  
  2. FROM table1  
  3. RIGHT [OUTER] JOIN table2  
  4. ON table1.column = table2.column;   

Image representation of Right Outer Join

Oracle Right Outer Join

Example

In this example, we are performing right outer join on the already created tables ?suppliers? and ?order1?.

The following example would return all rows from the order1 table and only those rows from the suppliers table where the join condition is met.

Execute this query

  1. SELECT order1.order_number, order1.city, suppliers.supplier_name  
  2. FROM suppliers  
  3. RIGHT OUTER JOIN order1  
  4. ON suppliers.supplier_id = order1.supplier_id;  

Output

Oracle Right Outer Join 2

Full Outer Join

The Full Outer Join returns all rows from the left hand table and right hand table. It places NULL where the join condition is not met.

Syntax

  1. SELECT columns  
  2. FROM table1  
  3. FULL [OUTER] JOIN table2  
  4. ON table1.column = table2.column;   

Image representation of Full Outer Join

Oracle Full Outer Join

Example

In this example, we are performing full outer join on the already created tables ?suppliers? and ?order1?.

The following example will return all rows from the ?suppliers? table and all rows from the ?order1? table and whenever the join condition is not met, it places the NULL value.

Execute this query

  1. SELECT suppliers.supplier_id, suppliers.supplier_name, order1.order_number  
  2. FROM suppliers  
  3. FULL OUTER JOIN order1  
  4. ON suppliers.supplier_id = order1.supplier_id;  

Output

Oracle Full Outer Join 2