Why Can't I Mix `mysql_` and `mysqli_` APIs in My PHP Code?

Mixing MySQL APIs in PHP

You have tried mixing the mysql_ and mysqli_ APIs in PHP, as shown in the code examples provided. However, this has resulted in error messages regarding resource incompatibility.

Compatibility Issues

mysql_ and mysqli_ are different APIs with separate implementations. They create resources that are not compatible with each other. Therefore, you cannot mix the two APIs in a single PHP script. Use only one API consistently throughout your application.

Valid Connections

To correctly establish a MySQL connection in PHP, follow the guidelines below:

• Use the mysqli_* functions exclusively for the mysqli_ API.
• Use the mysql_* functions exclusively for the mysql_ API.

Confirming Connection Status

To verify if a MySQL connection is valid, use the appropriate mysqli_connect_errno() or mysql_errno() function, depending on the API you are using. For example:

$con = mysqli_connect(...);
if (mysqli_connect_errno($con)) {
    echo "Failed to connect";
} else {
    echo "Connected";
}

or

$con = mysql_connect(...);
if (mysql_errno($con)) {
    echo "Failed to connect";
} else {
    echo "Connected";
}

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