PHP Interview Questions and answers

How we can delete duplicate records of a table where it has no unique or primary keys?

Mysql
delete from table where x = ‘aaa’ limit 1;

Mssql
set rowcount 1;
delete from table where x = ‘aaa’;
set rowcount 0;

What is a self join?

Self join is just like any other join, except that two instances of the same table will be joined in the query.