我有工作,我怎么想的声明,不过是它正确的方式,因为我有很多的IF语句,如果对性能的影响还是我应该知道采取不同的方法来获得最佳实践。这是从阅读文档创建的,所以我可能已经绕过它的日志方式。如果值是另一个表,然后选择特定的列
SELECT c.id, c.first_name, c.last_name,
IF(c.id IN (SELECT client_id FROM bookings) AND '1' IN (SELECT practitioner_id FROM bookings) , c.address1, NULL) as address1,
IF(c.id IN (SELECT client_id FROM bookings) AND '1' IN (SELECT practitioner_id FROM bookings) , c.address2, NULL) as address2,
IF(c.id IN (SELECT client_id FROM bookings) AND '1' IN (SELECT practitioner_id FROM bookings) , c.town, NULL) as town,
IF(c.id IN (SELECT client_id FROM bookings) AND '1' IN (SELECT practitioner_id FROM bookings) , c.county, NULL) as county,
IF(c.id IN (SELECT client_id FROM bookings) AND '1' IN (SELECT practitioner_id FROM bookings) , c.postcode, NULL) as postcode,
IF(c.id IN (SELECT client_id FROM bookings) AND '1' IN (SELECT practitioner_id FROM bookings) , c.email, NULL) as email,
IF(c.id IN (SELECT client_id FROM bookings) AND '1' IN (SELECT practitioner_id FROM bookings) , c.dob, NULL) as dob
FROM clients c
你到底想干什么? –
不,这绝对不是正确的,它极有可能是给你错误的结果,除非你在预订表中只有一行。借此这里'和“1” IN(SELECT practitioner_id FROM预订)'它完全无视它似乎检查如果c.id是表预订此前的说法。你可能认为它应该与之相关,但事实并非如此。 –
我试图只返回客户信息,如果他们已经与当前登录的人预订,否则登录的人只能看到名字和姓氏。声明给出了正确的输出,只是想确保我没有学习坏习惯。 – Bish25