Is there a performance improvement when using JOIN vs a WHERE clause? [duplicate]

Question

Is there a performance difference (or any other reason) to use a JOIN instead of a WHERE clause as per the code examples below:

ex1.

select *
from table_1, table_2
where table_1.id=table_2.id;

ex2.

select *
from table_1
    join table_2 on
    table_1.id = table_2.id;

Answer 1

You can refer: Bad habits to kick : using old-style JOINs(The link is for SQL Server but most of the points are valid for Oracle as well). Comma seperated JOINS are now discouraged. You should use the second format of JOINS as it is more readable and also it is highly recommended and widely used nowadays. And as far as performance is concerned there is no difference between the two syntax. Also the first format of JOINS (ie, the comma seperated) is pre - 1992 standard SQL join syntax.

Also in case of Oracle, when you had to use LEFT JOINS OR RIGHT JOINS then you had to use the old style of using (+) which was used to identify the table that is being outer joined to. So it was confusing and makes the query less readable. So the use of explicit JOINS(version 2 in your case) makes it more easier to understand and much readable.