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I can't find documentations on the key word join but I saw examples on the web using it.
I was doing some experiment with it in Oracle hr schema, where I have table departments:
deparment_namemanager_idlocation_idA table employees:
first_nameemployee_idAnd table locations:
location_idcityQuery should return the department_name, first_name of the manager of the department, and the city where the department is located.
The code using the keyword join seem to return the some result in comparison to using the keyword inner join
Code with join:
select d.department_name, e.first_name,l.city from departments d join employees e on d.manager_id=e.employee_id join locations l on d.location_id=l.location_id Code with inner join:
select d.department_name, e.first_name,l.city from departments d inner join employees e on d.manager_id=e.employee_id inner join locations l on d.location_id=l.location_id Is there a difference between the two condition, or am I just happen to stumble on a situation where they return the same results?
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Difference between JOIN and INNER JOINJOIN returns all rows from tables where the key record of one table is equal to the key records of another table. The INNER JOIN selects all rows from both participating tables as long as there is a match between the columns.
SQL Inner Join clause is the same as Join clause and works the same way if we don't specify the type (INNER) while using the Join clause. In short, Inner Join is the default keyword for Join and both can be used interchangeably.
'Inner join' is better, although it is equivalent to 'join' in performance as well as function.
1. The join operation which is used to merge two tables depending on their same column name and data types is known as natural join. Inner joins have a specific join condition. Here, the join operation is used to form a new table by joining column values of two tables based upon the join-predicate.
Query expressions 179 7.5 - joined table
3) If a qualified join is specified and a join type is not specified, then INNER is implicit.
INNER prefix is also optional. Before 9i, Oracle didn't follow ANSI rules, and didn't even support JOIN syntax.
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