What is the significance of "resource id #4" when using mysql_query in PHP?

When using mysql_query in PHP, "resource id #4" is a common issue that occurs when trying to directly output the result of a query. This happens because mysql_query returns a resource identifier, not the actual data. To solve this issue, you need to fetch the data from the result resource using functions like mysql_fetch_array or mysql_fetch_assoc before outputting it. 

// Perform a query
$result = mysql_query("SELECT * FROM table");

// Fetch data from the result resource
while ($row = mysql_fetch_assoc($result)) {
    // Output the data
    echo $row['column_name'] . "<br>";
}

Keywords

PHP mysql_query resource id database error

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