Sunday, 4 September 2016

How can I use mysqli / php to update all records after a query has already been executed?

I have a user form that sets a single record "current". No more than one record can be set to current at a time. So, I present the user a single drop down list, they choose the item they want to set current and hit "UPDATE" at the bottom of the form.



The PHP/Mysqli needs to go in and set all records column "current" to a value of 0 then update the one from the form to a value of "1".



Initially, I just did a simple count the number of rows, and run a bunch of queries to update the column to 0 or 1 if the loop counter = the id of the row. Well... that broke quick as I started doing testing on other portions and the index numbers got higher than the total number of rows. Yes, dumb way to do it initially!




Here's what I tried to do with the PHP / MySQL code:





// $link  is the database link defined elsewhere. This does work as I use it all over the place
$setCurrent = X; // This is the number passed from my form

$init_query = "SELECT id, current FROM myTable";

if ($stmt = $link->$prepare($init_query) {

$stmt->execute() or die ($stmt->error);
$stmt ->bind_result($id, $current)
while ($stmt->fetch()){
if ($id == $setCurrent){

$update_sql = "UPDATE myTable SET current ='1' WHERE id='".$setCurrent."'";
$stmt2 = $link->prepare($update_sql);
$stmt2->execute;

}


else {
$update_sql = "UPDATE myTable SET current ='0' WHERE id='".$id."'";
$stmt2 = $link->prepare($update_sql);
$stmt2->execute;
}
$stmt->close();






This fails and gives me a Fatal error: Uncaught Error: Call to a member function execute on boolean in .....



I am racking my brain over this and can't figure out what the heck is going on. Its been a few years since I have worked in PHP/MySql and this is my first forray into OO Mysqli. Please be gentle :)

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