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I am trying to update table in database using php but it gives mysql error mentioned above.

What I have tried:

PHP
$conn = new mysqli(Host,Username,Password,Database);
    
    $que="UPDATE `spare_parts` SET 
 `item_name`='$item_name', `brand`='$brand',
`buy_p`='$buy_r',
`sale_p`='$sale_r',
`qty`='$qty'
 WHERE `id`='$id' LIMIT 1";
        
    if($conn->query($que))
    {
        $msg = 'alert("Record updated successfully");';
    }
        else
        {
             $msg= $conn->error;
    }
Posted
Updated 4-Feb-23 18:11pm
v3
Comments
Richard MacCutchan 2-Oct-17 8:07am    
I suspect the use of back quotes is not correct. Check the documentation to be sure.
Member 13435586 2-Oct-17 8:33am    
This is not issue, because it works for others records but not working for some records it is one of them

1 solution

Probably, it's the data. If any of the data contains a quote character - "Mary's Beets" perhaps - it will terminate the input and the remained of the data will be used as SQL instructions. Never concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Use Parametrized queries instead.

When you concatenate strings, you cause problems because SQL receives commands like:
SQL
SELECT * FROM MyTable WHERE StreetAddress = 'Baker's Wood'
The quote the user added terminates the string as far as SQL is concerned and you get problems. But it could be worse. If I come along and type this instead: "x';DROP TABLE MyTable;--" Then SQL receives a very different command:
SQL
SELECT * FROM MyTable WHERE StreetAddress = 'x';DROP TABLE MyTable;--'
Which SQL sees as three separate commands:
SQL
SELECT * FROM MyTable WHERE StreetAddress = 'x';
A perfectly valid SELECT
SQL
DROP TABLE MyTable;
A perfectly valid "delete the table" command
SQL
--'
And everything else is a comment.
So it does: selects any matching rows, deletes the table from the DB, and ignores anything else.

So ALWAYS use parameterized queries! Or be prepared to restore your DB from backup frequently. You do take backups regularly, don't you?

See here: PHP: Prepared statements and stored procedures - Manual[^]
 
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Comments
Member 13435586 2-Oct-17 8:48am    
How can i use "PHP: prepared statements" for update query? please give a code example
OriginalGriff 2-Oct-17 8:51am    
Follow the link, read and learn.
Member 13435586 2-Oct-17 9:02am    
Sir i used it as but it's not working when i press update button the screen clears
$stmt = $conn->prepare ("UPDATE spare_parts SET qty = ? WHERE id = ? ");
$stmt -> bindParam('ss', $qty,$id);
$stmt -> execute();
$result = $stmt->get_result();

if($result)
{
$msg = 'alert("Record updated successfully");';
}

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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