Storm\Drivers\Base\Relational\Queries\QueryBuilder::Append PHP Method

    public final function Append($QueryString)
    {
        $this->QueryString .= $QueryString;
    }

 private function AppendOnDuplicateKeyUpdate(QueryBuilder $QueryBuilder, $TableName, array $Columns, array $PrimaryKeyIdentifiers)
 {
     $QueryBuilder->Append(' ON DUPLICATE KEY UPDATE ');
     $FirstPrimaryKey = true;
     foreach ($QueryBuilder->Delimit($Columns, ',') as $ColumName => $Column) {
         $ColumnIdentifier = [$TableName, $ColumName];
         if ($FirstPrimaryKey && $Column->IsPrimaryKey()) {
             /*
              * Ugly fix/hack to prevent mysql from updating primary key when encountering
              * a duplicate value on a seperate unique constraint. Sadly Mysql does not support
              * the more robust 'MERGE' operation. Furthermore there is no clean way to throw a 
              * conditional runtime error in Mysql reliably.
              * 
              * Example: Persisting a account entity with a unique username, if the user changes
              * their username and and a duplicate username exists, mysql could attempt to update
              * the other duplicate row with the new values/primary key. This should not be an 
              * issue as then it will fail with a duplicate primary key but could lead to some 
              * wacky edge cases that I want no part in.
              */
             $QueryBuilder->AppendIdentifier('# = IF(', $ColumnIdentifier);
             foreach ($QueryBuilder->Delimit($PrimaryKeyIdentifiers, ' AND ') as $PrimaryKeyIdentifier) {
                 $QueryBuilder->AppendIdentifier('# = VALUES(#)', $PrimaryKeyIdentifier);
             }
             $QueryBuilder->Append(',');
             $QueryBuilder->AppendIdentifier('VALUES(#)', $ColumnIdentifier);
             $QueryBuilder->Append(',');
             $QueryBuilder->Append('(SELECT 1 UNION ALL SELECT 1))');
             $FirstPrimaryKey = false;
         } else {
             $QueryBuilder->AppendIdentifier('# = VALUES(#)', $ColumnIdentifier);
         }
     }
 }