Search value in table, if the value is not found, auto insert - php

Question

Is it possible to search for a value in MySQL and if the value is not found, automatically insert that value?
For example:
This is my table. The id is auto increment, the case id is inserted by me
when I search for a number on my search box. If that number is not inside the table, it will auto insert it into the table.
id| case id
1 | 324
2 | 789
3 | 314
when me search 123 on my search box.that number of 123 is not in my table so that number of 123 will auto insert into my table.
id | case id
1 | 324
2 | 789
3 | 314
4 | 123
Is this possible?
here is my code
mysql_select_db($database_connection_db, $connection_db);
$query_viewAduan = mysql_query("SELECT No_KP, COUNT(*) FROM aduan_tidak_hadir WHERE No_KP LIKE '%".$no_kp."%' GROUP BY No_KP;");
while ($row = mysql_fetch_array($query_viewAduan))
{
if (!$row['COUNT(*)'])
{
echo 'satu';
}
else if ($row['COUNT(*)'] == '1')
{
echo 'dua';
}
else if ($row['COUNT(*)'] == '2')
{
echo 'tiga';
}
}

Answer 1

Yes this is possible but not with simple sql statements. This has to be done with an extension of sql called PLSQL. If you know PLSQL then continue reading or otherwise stop right here and learn it befor you read this full answer.
Here's the code for you question:
declare numb my_table.case_id%type
begin
select case_id into numb from my_table where numb=case_id;
exception
when no_data_found then
insert into my_table values(/*you said the id auto_increments so I'm leaving this one out*/,numb);
end;
Since I didn't know the name of your table I just called it my_table. Try this and it should work.

Answer 2

A quick note before I move to an answer. Any time you ask a question, whether it be on the web or to another person, you should have tried something already. This is true for any subject. If you want to drive your car, you must first try to start it. It might be obvious that you tried that, but in a more technical subject, we need to know that you in fact did try something, and that what you tried did not work. A lot of times these questions get asked because the users have in fact tried nothing at all. It is important that you try something, because that is your real learning experience. Just following a set of instructions given to you here will not help you in the future.
Now on to helping you figure out your problem. You have flagged your question as a PHP and MySQL question, which suggests that you don't need to do it in a single MySQL query. I won't give you the code to do it, but I will point you in a direction for some sample code.
Let's break down your question into the actual steps:
Search value in table
This is the first part of your question. This is a basic select statement. I'm sure you can figure it out. If not, google for MySQL select.
if the value is not found
This is the second part of your question that essentially defines what you must do in PHP. You need to check if the value was not found. You need to look at the results of select statement from your search value in table step and determine whether or not it was empty or contained results.
auto insert
At this step, based on your last step if the value is not found, we can determine whether or not we should insert the value. For instructions on how to do an insert, Google mysql insert.