PHP statements for determining whether the record set is not empty after executing SQL statements

{Code...} Why does this user not echo?

  0) {echo 'record set is not blank !!!!!, This user name already exists. '; // perform the update operation} else {// Add data}?>

Why does this user not echo?

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  0) {echo 'record set is not blank !!!!!, This user name already exists. '; // perform the update operation} else {// Add data}?>

Why does this user not echo?

Remove $ result, which is a resource type. The resource type cannot be boolean.

Solved? If the problem persists, Print $ con first, or remove $ con from $ result = mysql_query ($ SQL, $ con). The last connection is enabled by default, if yes, or if it is printed out as null, the connection object is not connected successfully. Check whether the connection object is successfully assigned a value during initialization? The reason for the failure is that the user password and connection address are incorrect. I forgot $ this-> conn and directly mysql_connect, then, the value of $ this-> conn is null. Haha

Yes.!empty($result)