Question

I have two tables called clients, they are exactly the same but within two different db’s. Now the master always needs to update with the secondary one. And all data should always be the same, the script runs once per day. What would be the best to accomplish this.

I had the following solution but I think maybe theres a better way to do this

$sql = "SELECT * FROM client";
$res = mysql_query($conn,$sql); 
while($row = mysql_fetch_object($res)){
    $sql = "SELECT count(*) FROM clients WHERE id={$row->id}";
    $res1 = mysql_query($connSecond,$sql);
    if(mysql_num_rows($res1) > 0){
       //Update second table
    }else{
       //Insert into second table
    }
}

and then I need a solution to delete all old data in second table thats not in master.

Any advise help would be appreaciated

Answer 1

You can use mysql INSERT ... SELECT like this (but first truncate the target table):

TRUNCATE TABLE database2.client;
INSERT INTO database2.client SELECT * FROM database1.client;

It will be way faster than doing it by PHP.

And to your notice:

As long as the mysql user has been given the right permissions to all databases and tables where data is pulled from or pushed to, this will work. Though the mysql_select_db function selects one database, the mysql statement may reference another if you use complete reference like databasename.tablename