PHP/mySQL noob question

[alexxz4]

Hi,
This is my second day programming in PHP/mySQL. Im trying to delete an entry.
My table has three rows: name, val1, val2 and im trying to delete a row which has name 'stevenjones'

[B][U]function[/U] db_delete($nm) {
@mysql_query("DELETE FROM table WHERE name=$nm");
}

It says
[/B]Error: Unknown column 'stevenjones' in 'where clause' 0

 

[DeadBattery]

I think the problem is you are trying to delete a column, not a row.
That is what I think, but I am not experienced with MySQL.

 

[alexxz4]

Ok, i got it, it supposed to say:

function db_delete($nm) {
@mysql_query("DELETE FROM table WHERE name='{$nm}'");
}

 

[Adam01]

You dont need the {} around the variable.
Whats the @ for?

 

[taekwondokid42]

When I'm trying to delete something, my syntax usually looks like:

//mysql_connection

mysql_query("DELETE FROM example WHERE id = $example_id");


I've never found that more is necessary.

 

[DeadBattery]

What was the difference between the first and second pieces of code?

 

[alexxz4]

You dont need the {} around the variable.
Whats the @ for?

Well i tried using it without {} or without single quotes and it didnt work.
@ supposed to block any errors returning from the sql call, ive read.

 

[LHVWB]

The mysql_query() function requires the '$var' or {$var}, to make the variable work. Otherwise it will not be treated as a php variable. You should not need both of them at the same time.

 

[cowctcat]

why dont you just go into phpmyadmin and delete the row there its as simple as clicking a button.

 

[woiwky]

why dont you just go into phpmyadmin and delete the row there its as simple as clicking a button.

That hardly helps him with learning php/mysql. And what's more, it's completely illogical to have deletions done by a human when the script can take care of them on the spot.

The mysql_query() function requires the '$var' or {$var}, to make the variable work. Otherwise it will not be treated as a php variable. You should not need both of them at the same time.

Curly braces in a string (with a variable enclosed, of course) only really need to be used when accessing a value in an associative array, otherwise you'll get a parse error for trying to do that. For any other instance, their use is usually merely to help with clarification of the string. Meaning there should be no difference between "$var" and "{$var}".

For a query like the one in the OP, single quotes need to be put around the variable to specify to mysql that the value is a string. Otherwise it assumes you want the value in column 'name' compared to the value in column $nm, which could be any existent or nonexistent column.

 

[expose]

[B]function db_delete($nm) {[/B]
[B]@mysql_query("DELETE FROM table WHERE name=$nm");[/B]
[B]}[/B]

Try this:

//open a database connection
$conn = mysql_connect("localhost", "mysql_username", "mysql_password");
mysql_select_db("db_name",$conn);
 
function db_delete($nm) {
 
$query_delete = "DELETE FROM `table` WHERE `name` = '$nm'";
$result = mysql_query($query_delete,$conn) or die(mysql_error()."<br /><br /><h3>An Error occured while trying to handle your request</h3>");
 
}

I always execute my queries using the above structure, as it helps cut down on redundant typing. Furthermore, you don't want to silence errors, you want them displayed in a friendly manner so users can contact you with them so that you can resolve them.