select Customer from(SELECT CustomerName AS Customer FROM Customers) cus;请问这里的cus起什么作用

Select all cus_name city from customer; Select all cus_name,city from customer; 有何不同?Select all cus_name city from customer; Select all cus_name,city from customer;这两条语句查询的结果为什么不一样?第二句的逗号有什么 select Customer from(SELECT CustomerName AS Customer FROM Customers) cus;请问这里的cus起什么作用 select * from book limit , org.hibernate.QueryException:could not resolve propertycould not resolve property:customers of:com.betex.crm.sysmanage.domain.User [ select u from com.betex.crm.sysmanage.domain.User u left outer join u.customers as customer where customer.id=?]这 select * from a union select * from b 能详细说下么 select from 表 和select from [表]有什么不同? select count(*) from 怎么使用 select count(1) from emp select * into dept2 from dept 1' union select * from [ADM] union select * material determination?Hi peopleI have a scenario where my client wants 1.His customer to select a material if a certain material is not available2.The second material should be amongst a list of materials say 4/5 from which the customer can choose.3 请问 select top 1 1 from ... // IF EXISTS (SELECT name FROM m select * into b from a where 11 SQL 语句 SELECT * FROM {{table}} WHERE `fleet_end_time` CUSTOMER customer SELECT