SQL查询替代为LEFT OUTER /优化JOIN

Question

我有以下查询：

SELECT 
    `pokemon_moves`.`pokemon_move_method_id`, 
    `pokemon_moves`.`level`, 
    `move`.`id`, 
    `move`.`name` 
FROM 
    `pokemon_moves` 
LEFT OUTER JOIN 
    `moves` `move` ON 
     `move`.`id` = `pokemon_moves`.`move_id` 
WHERE 
    `pokemon_moves`.`pokemon_move_method_id` < '4' AND 
    `pokemon_moves`.`pokemon_id` = '2' AND 
    `pokemon_moves`.`version_group_id` = '6' 
ORDER BY 
    CAST(`pokemon_moves`.`level` as INTEGER) ASC, 
    `move`.`name` ASC 

这是有点慢，我想那是因为moves查询表在pokemon_moves表的每一行，而不是只符合WHERE条款的。写这个查询有什么更好的选择？

请注意，在这个（外部）表中的整数被存储为文本

Answer 1

尝试使用内部连接，并把你的WHERE条件到JOIN语句。例如：

SELECT 
    `pokemon_moves`.`pokemon_move_method_id`, 
    `pokemon_moves`.`level`, 
    `move`.`id`, 
    `move`.`name` 
FROM 
    `pokemon_moves` 
INNER JOIN 
    `moves` `move` ON 
    `pokemon_moves`.`pokemon_id` = '2' AND 
    `pokemon_moves`.`version_group_id` = '6' AND 
    `pokemon_moves`.`pokemon_move_method_id` < '4' AND 
    `move`.`id` = `pokemon_moves`.`move_id` 
ORDER BY 
    CAST(`pokemon_moves`.`level` as INTEGER) ASC, 
    `move`.`name` ASC