How to check if "value does not exists" in sqlite column using C++

I have a table "SiteCode" with following schema :

CREATE TABLE SiteCode(
ID INTEGER PRIMARY KEY,
Code TEXT(3) UNIQUE NOT NULL DEFAULT 0);

Through the following code I can Open a DB & Access the elements of DB and perform the query execution perfectly.

Now I wish to add a small code snippet which could check if the element that a user wish to delete exists .

For example: Suppose table SiteCode have following Entries in Code column : 400, 401, 402 and 403 and user enters 444 as the input to DELETE query then it shall return an error.

At present, if a user enters 444 as input to the query then that query gets executed successfully without checking the Code column and without any Error.

How do i approach this problem. Kindly Help.

void DELETE_Site_Code()
{
     int CodeA;

     int rc = sqlite3_open("/DBsqlite3/empdbv3.db", &db);

     if (rc != SQLITE_OK) {       
         cerr << "Cannot open database [ " << sqlite3_errmsg(db) << " ]" << endl;        
         sqlite3_close(db);        
     }


     sql = "DELETE FROM SiteCode WHERE Code= @Code;";

     rc = sqlite3_prepare_v2(db, sql, -1, &stmt4, 0);

     if(SQLITE_OK != rc) {
         cerr << "Failed to PREPARE DELETE statement for SiteCode Table [ " << sqlite3_errmsg(db) << " ]" << endl;
         sqlite3_close(db);
         exit(1);
     }

     else{
         int Code_x = sqlite3_bind_parameter_index(stmt4, "@Code");

         cout<< "Enter the Site Code That you wish to DELETE from table-SiteCode\n"<< endl;
         cin>>CodeA;                                                     

         if(cin.fail()) {
             cout<<"\nPlease enter only digits\n"<<endl;
         }
         else {
             if((CodeA >= 000) && (CodeA <= 998)) {
                 sqlite3_bind_int(stmt4, Code_x, CodeA);
             }
             else {
                 cout<< "Valid Site Code Should be between 000 to 998\n" <<endl;
             }
         } //else loop of (cin.fail) ends here
     }

    int step = sqlite3_step(stmt4);

    if(SQLITE_DONE != step) {
        cout<<"\nERROR while inserting into table\n"<< endl;
    } 
    else {
        cout<<"\nRecord DELETION completed"<<endl;
    }

    if(step == SQLITE_ROW){
        cout<< sqlite3_column_text(stmt4, 0) << endl;
        cout<< sqlite3_column_text(stmt4, 1) << endl;
    }


    sqlite3_finalize(stmt4);
    sqlite3_close(db);

}