Question

Is there any difference between

SELECT *
FROM TABLE_A a
JOIN TABLE_B b
  ON a.propertyA = b.propertyA        

And the query

SELECT * from TABLE_A a, TABLE_B b where a.propertyA=b.propertyA.

Answer 1

INNER JOIN is ANSI (SQL-92) syntax which you use on the first one. It is generally considered more readable, especially when you join lots of tables.

The WHERE syntax (SQL-89) is more relational model oriented. A result of two tables JOIN’ed is a cartesian product of the tables to which a filter is applied which selects only those rows with joining columns matching.

It’s easier to see this with the WHERE syntax.

I’d rather go on the ANSI type join because if you some how omit the ON clause, an error is generated whereas the old type of join if you omit the condition on where clause will not produce an error message and thus it will generate cartesian product.