Duplicate entry '0' for key 1

[dmccabe]

Hmmm I am trying to create an admin function to create tables and insert data in to them.

 

However it should only create the table if it doesn't exist.

 

<?php 

/* Function to Create Main Category Tables */
function createmaintable($cat_name,$cat_url){
$sql_createtable = "CREATE TABLE IF NOT EXISTS categories (cat_id INT NOT NULL ,cat_name VARCHAR( 255 ) NOT NULL ,cat_url VARCHAR( 255 ) NOT NULL ,PRIMARY KEY ( cat_id )) ENGINE = innodb";
mysql_query($sql_createtable);
if (isset($cat_name)) {		
	$sql_insertmaincat = "INSERT INTO categories (cat_id ,cat_name ,cat_url )VALUES ('', '$cat_name', '$cat_url')";
	if (mysql_query($sql_insertmaincat)) {
		$result = "Success";
	} else {
		$result = mysql_error();
	}
} else {
	$result = "No Catergory Name Specified";
}
return $result;
}

  
?>

 

The first time I run this, then it works perfectly.

 

Second and any subsequent time it returns

 

Duplicate entry '0' for key 1

 

Any thoughts?

[effigy]

cat_id should be AUTO_INCREMENT.

[dmccabe]

Thanks for advice, i added the auto_increment, but now it doesnt work at all, I have deleted the table and tried again and now it fails on the first try with the same error.

 

 

[effigy]

Check for errors when running $sql_createtable. Also, trying changing cat_id's value in the INSERT SQL to NULL.

[mushroom]

If "cat_id" is "AUTO_INCREMENT" there is no need to include in your second query at all, the field and value will fill in automatically.