每次刷新时如何重新声明/重新定义MySQL用户功能？

Question

Is it possible to redeclare a MySQL function every time you refresh, this is my code

mysql_query("
DROP FUNCTION IF EXISTS Add_num;
CREATE FUNCTION Add_num(LAT_A INT)
RETURNS INT
READS SQL DATA
DETERMINISTIC
BEGIN
DECLARE Ans BIGINT;
SET Ans = LAT_A + 2;
RETURN Ans;
END");

even though I have the line DROP FUNCTION IF EXISTS Add2; the function stays the same when refreshing. For example I changed the 2 to 3 in the line SET Ans = LAT_A + 2; and then refreshed and it still adds 2 not 3.

Answer 1

I have written solution for you, but here I have used mysqli as you would be aware about mysql_query() doesn't accept semicolon(;) and can execute only one query at a time.

Code is as below :

$mysqli = new mysqli("localhost", "root", "", "test");

if (mysqli_connect_errno()) {
    printf("Connect failed: %s
", mysqli_connect_error());
    exit();
}

if (!$mysqli->query("DROP FUNCTION IF EXISTS Add_num") ||
    !$mysqli->query("CREATE FUNCTION Add_num(LAT_A INT) RETURNS INT  READS SQL DATA  DETERMINISTIC  BEGIN  DECLARE Ans BIGINT;  SET Ans = LAT_A + 4;  RETURN Ans;  END;")) {
    echo "Function creation failed: (" . $mysqli->errno . ") " . $mysqli->error;
}
$select_qry = " SELECT Add_num(6) as result";
$result = $mysqli->query($select_qry);

if ($result) {
    $row = $result->fetch_assoc();
    echo "Result is :{$row['result']}";
}

$mysqli->close();