Accesing mysql database from threads

Question

Hi
dont know if this is the right place for this
I'm building a server-client application, on sever's side I create a thread for every client who can request several operations over a mysql database (insert, delete, update, etc), at some point 2 clients can request the same operation over the same registry (2 clients trying to delete the same registry, for example), I try to avoid that to happend, so before doing any operation over the database I check the correct status (a registry must exist to delete, or not exist to create, for example), this is the code that makes that (for inserting a registry):
//first I make sure the registry does not exist
sql = "SELECT id_grupo FROM adm_grupo WHERE nombre_grupo = '" + nomGrupo + "'";
res = bd.ConsultarSQL(sql);
//If already exist, the operation is rejected
if (res.next()) {
    EnviarError("Error al Crear el Grupo: Ya existe ese nombre");
     return -1;               
//Check point ends
//If not, the insert statement is made
sql = "INSERT INTO adm_grupo VALUES (NULL,'" + nomGrupo + "','N')";however, since it could be 2 threads (every thread is an object) doing that, the first one can pass the check point and stop because its processor time is over, so the second can start its insert process and pass the check point too (because the first one didn't have enough time to insert the registry), then both registries are inserted causing a logical error, I thought in fixing that problem using the synchronized keyword for the functions, but I read that keyword blocks 1 object that can be accesed for several threads, but in my case I have several threads, everyone accesing its own object, so I'm not sure if the synchronized will work, I dont know any other solution to this,
thnx in advance for any help

Answer 1

Sure.  But test it.  You'll need to test it regardless, just to make sure it all works.
In general, I usually prefer to have the backup tool create the initial SQL database archive on the primary server, zip it, and to then have the backup server in a trusted network location pull the database archive over to the backup server.  (It can then unzip it or process it as needed.)  With this, the primary server doesn't have access to the backups, nor to the backup server. This intended to isolate the access that a breach of the primary server might permit.