I want submit my forms data to the sql database but before submission
,the values of the fields must be checked with values in database....in
other words imagine a room reservation form, before form is submitted
to the database it should be investigated that this room in requested
time has been reserved before or not if yes showing a message and do
not insert a new row into the database...how can I do that ..what is
the solution for checking with database fields and then submit the
forms?

thanks