如果值存在，则MySQL更新；如果不存在，则插入MySQL？

Question

$sql_career = "REPLACE INTO career
         (id, battletag, lastHeroPlayed, lastUpdated, monsters, elites, hardcoreMonsters, barbarian, crusader, demonhunter, monk, witchdoctor, wizard, paragonLevel, paragonLevelHardcore)
         VALUES
         ('', '$battletag', '$lastHeroPlayed', '$lastUpdated', '$monsters', '$elites', '$hardcoreMonsters', '$barbarian', '$crusader', '$demonhunter', '$monk', '$witchdoctor', '$wizard', '$paragonLevel', '$paragonLevelHardcore')";

ID auto increments. battletag is unique.

Everything else changes over time. So I want to replace or update an entry if the battletag already exists without it making a new id . If it doesnt exist I want it to make a new entry letting the id auto increment for that unique battletag .

---

This works with one problem:

 $sql_career = "
    insert INTO career
      (id, battletag, lastHeroPlayed)
    VALUES
      (NULL, '$battletag', $lastHeroPlayed)
    on duplicate key
      update lastHeroPlayed=$lastHeroPlayed;
 ";

If I, for instance, load in two unique rows, the ID auto increments to 1 and then 2 for each. Then if I load up a row that has a duplicate of the unique key of one of the existing rows (and it then updates as it should) this actually triggers the auto increment. So if I then add in a third unique row, its number will be 4 instead of 3.

How can I fix this?

Answer 1

You want to use the on duplicate key ... update syntax instead of replace into.

Define a unique column (primary or unique index) then check it in your statement like this:

INSERT INTO table (a,b,c) VALUES (1,2,3),(4,5,6)
  ON DUPLICATE KEY UPDATE c=VALUES(a)+VALUES(b);

The benefit of using this over a replace into is that replace into will always delete the data you have already and replace it (sort of as the command name implies) with the data that you are supplying the second time round. An update on... statement however will only update the columns you define in the second part of it - if the duplicate is found - so you can keep information in the columns you want to keep it in.

Basically your command will look something like this (Abbreviated for important columns only)

$sql_career = "
    insert INTO career
        (id, battletag, heroesKilled)
    VALUES
        ($id, '$battletag', $heroesKilled)
    on duplicate key
        update heroesKilled=heroesKilled+1;

";

Again, remember that in your table, you will need to enforce a unique column on battletag - either a primary key or unique index . You can do this once via code or via something like phpMyAdmin if you have that installed.

Edit: Okay, I potentially found a little gem (it's about a third of the way down the page) that might do the trick - never used it myself though, but can you try the following for me?

$sql_career = "
    insert ignore INTO career
        (id, battletag, heroesKilled)
    VALUES
        (null, '$battletag', $heroesKilled)
    on duplicate key
        update heroesKilled=heroesKilled+1;

";

There seems to be collaborating evidence supporting this in this page of the docs as well:

If you use INSERT IGNORE and the row is ignored, the AUTO_INCREMENT counter is not incremented and LAST_INSERT_ID() returns 0, which reflects that no row was inserted.