INSERT IF NOT EXISTS with NULL value

Question

I have two tables: tags and linking table photos_tags. I want to add a new tag, so I check if the tag is already in the tags table and if not I insert one. My tables look something like this: tags(id, name), photos_tags(photos_id, tags_id). Now I tried to do this with:

IF NOT EXISTS (SELECT * FROM tags WHERE name=*tagsName*)  
  INSERT INTO tags VALUES (NULL, *tagsName*); --NULL used for autonumbering

I've also tried:

INSERT INTO tags (  
  SELECT NULL, *tagsName*  
  WHERE NOT EXISTS (  
    SELECT * FROM tags  
    WHERE name=*tagsName*  
  )  
);

Both statements result in syntax errors:

• in the first statement near if
• in the second statement near select

What should my query look like?

Solution 1

Create a UNIQUE constraint on tags.name and use this:

INSERT  OR IGNORE
INTO    tags (id, name)
VALUES  (NULL, 'tagsName')

If for some reason you can't or don't want to do this, use this:

INSERT
INTO    tags (id, name)
SELECT  NULL, 'tagsName'
WHERE   NOT EXISTS
        (
        SELECT  NULL
        FROM    tags
        WHERE   name = 'tagsName'
        )

Solution 2

INSERT INTO tags (name)
SELECT 'tagsName'
WHERE NOT EXISTS (SELECT 1 FROM tags WHERE name = 'tagsName');

OR

INSERT  OR IGNORE
INTO tags (id, name)
VALUES (NULL, 'tagsName')

if you have a unique constraint