Delete MySQL row - php

Question

I am using PHP 7 and the latest mysql on ubuntu 16.10. This is the current code I have
<?php
$dbhost = 'localhost:3036';
$dbuser = 'root';
$dbpass = 'password';
$conn = mysql_connect($dbhost, $dbuser, $dbpass);
$sql = "DELETE FROM databasetable WHERE columnA LIKE '%Test7%'" ;
mysql_select_db('jdbdev');
$retval = mysql_query( $sql, $conn );
if(! $retval ) {
die('Could not delete data: ' . mysql_error());
}
echo "Deleted data successfully\n";
mysql_close($conn);
?>

Answer 1

Should change to below query
DELETE FROM databasetable WHERE columnA like '%Test7%'
There is difference between = and like operator

Answer 2

It's not very clear for me what you are trying to accomplish using this:
WHERE columnA = '%Test7%'" ;
Is the percent sign a literal that should match just like that? As you probably know, percentage sign is a wildcard in mysql and it should be use with LIKE rather than equal.
In this case, your condition will be:
WHERE columnA LIKE '%Test7%'`

Answer 3

If you want to use wildcard % then you have to use LIKE instead of =, so change your sql to:
"DELETE FROM databasetable WHERE columnA LIKE '%Test7%'"
Also, mysql functions are vulnerable to sql injection, you should use mysqli or even better PDO to manage your database.

Answer 4

Try:
<?php
$dbhost = 'localhost';
$dbuser = 'root';
$dbpass = 'password';
$db_name = 'jdbdev';
$conn = mysqli($dbhost, $dbuser, $dbpass, $db_name);
try{
if($conn->connect_error){
echo 'Could not establish connection to database because '.$conn->connect_error;
}
}catch(Exception $ex){
echo $ex->getMessage();
exit;
}
$sql = "DELETE FROM databasetable WHERE databasetable.columnA LIKE '%Test7%'";
$retval = $conn->query($sql);
if($retval === FALSE) {
die('Could not delete data: ' . mysql_error());
}
echo "Deleted data successfully\n";
mysql_close($conn);
?>
Sometimes, you have to reference the database table in front of the column

Answer 5

$sql = "DELETE FROM databasetable WHERE columnA = '%Test7%'" ;
should be columnA like '%test7%'
$sql = "DELETE FROM databasetable WHERE columnA like '%test7%'
Like and = both are different.

Answer 6

Assuming you're trying to delete all the rows where columnA contains the test "Test7", you need to use the like operator, not the = operator:
DELETE FROM databasetable WHERE columnA LIKE '%Test7%'
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