Insert data when empty and update it when data exist

With so many function provided in mysql plus lazy, It seem like finding gem for replace my old approach icon smile Insert data when empty and update it when data exist

duplicate data isn’t good, I must search for exisiting data, in general : insert data to table when no data with that value exist and update table if data exist

For example :

I have table A with field :

1. id, integer 11 primary key auto increment

2. name, varchar 25

3. address, varchar 100

4. phone, varchar 20

5. username, varchar 10 unique

a common operation to insert data is :

Checking for data, ex :

$check_data = mysql_query("select * from A where username =’$user’");
if(mysql_num_rows($check_data)>0) {
do update data

mysql_query("update A set bla..bla..bla");
}
else {
insert query here
mysql_query("insert into A bla..bla..bla");
}

after find "replace()"

mysql_query("replace into A (field1,field2)  values(‘values1′,’values2′)")

Yes, I still need to do research for another ‘glitch’ possibility in current application.

From mysql manual :

As long index exist for that table, like primary key or unique for helping mysql to find duplicate data or not.

Yes, replace don’t insert please  icon wink Insert data when empty and update it when data exist