public Action:CreateItemsTables(Handle:Timer)
{
    new String:sQuery[128 * 32];
    Format(sQuery, sizeof(sQuery), "CREATE TABLE IF NOT EXISTS `Items`");
    Format(sQuery, sizeof(sQuery), "%s (`PlayerID` VARCHAR(24) PRIMARY KEY,");  //Assuming this is your AuthString
    new iCap = MAXITEMS - 1;
    for(new i = 1; i < MAXITEMS; i++)
        Format(sQuery, sizeof(sQuery), "%s `Column_%d` int(12) NULL%s", sQuery, i, ((i == iCap) ? ")", ",");
    SQL_TQuery(hDatabase, SQLErrorCheckCallback, sQuery);
}