SQL Select＆amp;连接表以显示结果

Question

我刚刚开始学习数据库和SQL，我一直在研究一个我无法解决的问题。这是我尝试做的，给出了两个名为CHARTER和CUSTOMER的表：

Give the relational algebra statement (or SQL) as well as the table that would 
result from applying SELECT & JOIN relational operators to the CHARTER and 
CUSTOMER tables to return only the CHAR_TRIP, CUS_LNAME and CHAR_DESTINATION 
attributes for charters flown by pilot 109. 

Note that 109 is sometimes the pilot and other times the co-pilot. 
Display all these flights.

这是我尝试过的SQL：

select CHAR_TRIP, CUS_LNAME, CHAR_DESTINATION from CHARTER natural join CUSTOMER where CHARTER.CHAR_PILOT and CHARTER.CHAR_COPILOT="109"; 

但这似乎并没有给我我想要的东西;我应该得到6条记录，但我只得到3.我认为这可能是由于SQL中的某些内容。我是否忽略了我的代码？

Answer 1

不确定Mysql是否有一些特殊语法，但尝试分离WHERE条件：

select CHAR_TRIP, CUS_LNAME, CHAR_DESTINATION 
from CHARTER natural join CUSTOMER 
where CHARTER.CHAR_PILOT ="109" 
or CHARTER.CHAR_COPILOT="109"; 

我将第二个更改为or，因为109可以是主要飞行员或副驾驶员。