php - 通过将两个 MySQL 查询合并为 1 来简化它们？

Question

我有两个非常相似的 MySQL 查询，但是它们在特定的 WHERE 子句(type)上返回一个 COUNT()，所以我想知道它们是否可以合并到 1 个查询中，因为只有 WHERE 子句 (type) 区分了两者？

查询 1:

SELECT COUNT(referral_id) AS in_count
FROM   referrals
WHERE  author = '{$author}'
       AND type = 'in'
       AND ip_address = '{$ip_address}'
LIMIT  1 

查询 2:

SELECT COUNT(referral_id) AS out_count
FROM   referrals
WHERE  author = '{$author}'
       AND type = 'out'
       AND ip_address = '{$ip_address}'
LIMIT  1 

非常感谢所有帮助:B

Answer 1

SELECT SUM(IF(type='in',1,0)) as in_count, 
       SUM(IF(type='out',1,0)) as out_count
FROM   referrals
WHERE  author = '{$author}' AND
       ip_address = '{$ip_address}'
LIMIT  1