mysql_query & update query is not executing

Question

I am trying to run an update for a specific row of a table and increase by one the content of a column each time the update runs. However at certain times the query doesn't run and it does not produce an exception either. Does anyone know why this might be happening? I have tried the following:

$intVersion = $this->intVersion + 1;
$strSql=<<<EOT
UPDATE $this->strQueryTable SET version = '$intVersion' WHERE id = $this->id;
EOT;
$blnQueryOk = mysql_query ( $strSql );

$intVersion = $this->intVersion + 1;
$strSql =<<<EOT
UPDATE $this->strQueryTable SET version = $intVersion WHERE id = $this->id;
EOT;
$blnQueryOk = mysql_query ( $strSql );

$strSql =<<<EOT
UPDATE $this->strQueryTable SET version = version + 1 WHERE id = $this->id;
EOT;
$blnQueryOk = mysql_query ( $strSql );

and under all cases:

if (!$blnQueryOk) {
   throw new Exception(mysql_error ());
   return false;
}

All of them fail to update some times without producing an exception.

Answer 1

1. It might be that it is actually the database connection call which is failing (due to some database related issue like a network problem or too many mysql connections etc.). You could try doing this:
   • After your mysql_connect() call, verify that the db connection resource has really been created, and in case of a false return value, start throwing an exception.
     
     
2. A very common reason behind mysql_error() not producing anything is when you have multiple database connections open in the same process. To avoid this:
   • In all your mysql_query() and mysql_error() calls, also start passing the db connection resource as a parameter.