CODEWITHSUNDEEP
phphtmlmysql
emen
emen

Reputation: 6308

Avoid duplicated record in database

// Check to see if p_name exists
    $sql = mysql_query("SELECT patient_name FROM patient WHERE patient_name = '" . $p_name . "'");
    if (mysql_num_rows($sql) == 0){
       // patient database
       mysql_query("INSERT INTO patient (patient_name)
                   VALUES ( '$p_name' )") or die (mysql_error());
       }
    else
       die ("Patient name exist!");

Why does it still insert new record even if the patient_name exist in the database?

Is if (mysql_num_rows($sql) == 0) correct?

Upvotes: 1

Views: 92

Answers (1)

Marc B
Marc B

Reputation: 360682

The query probably failed for some reason. That means $sql is a boolean FALSE. You try to pass that FALSE to mysql_num_rows(), which also fails, since it expects to get a result handle. That means mysql_num_rows() also returns a boolean FALSE. In PHP, false == 0 is TRUE, so you execute your insert statement.

NEVER assume a query has succeeded. ALWAYS check for failure. That means, as a bare minimum, you have:

$result = mysql_query(...) or die(mysql_error());
                          ^^^^^^^^^^^^^^^^^^^^^^

Upvotes: 1

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