Question

Possible Duplicate:
How to 'insert if not exists' in MySQL?

There is SQL table:

CREATE TABLE IF NOT EXISTS `MyTable` (
  `id` smallint(6) NOT NULL AUTO_INCREMENT,
  `MyVar` varchar(40) DEFAULT NULL,
  PRIMARY KEY (`id`)
) 

And there are two PHP arrays arr1[]=array("abc","bcd") and arr2[]=array("abc","cde").

Let’s say I have saved arr1[] values to SQL table. Now let’s suppose I need to save arr2[] values to the same SQL table. Which SQL INSERT query do I need to write in order to avoid duplicate saving of “abc” entry? The result must be:

MyTable:
1  |  abc
2  |  bcd
3  |  cde

but NOT:

MyTable:
1  |  abc
2  |  bcd
3  |  abc
4  |  cde

UPDATE:
Maybe the MyTable should be created/defined in such a way that duplicate entries are ignored?

Answer 1

Make the MyVar as UNIQUE in your table.

Like this:

CREATE TABLE IF NOT EXISTS `MyTable` (
  `id` smallint(6) NOT NULL AUTO_INCREMENT,
  `MyVar` varchar(40) DEFAULT NULL,
  PRIMARY KEY (`id`),
  UNIQUE INDEX `myvaridx` (`MyVar`)
);

or, if you’re unable to recreate the table, alter it using

ALTER TABLE `request`
ADD UNIQUE INDEX `myvaridx` (`MyVar`)