为什么 select * from student left outer join takes on true where student.id=takes.id; 运行不了为什么 select * from student left outer join takes on true where student.id=takes.id; 运行不了 这是书上的

select max(account_id ) from(select top 5 account_id from account)子查询没起作用为什么? select * from book limit , 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 year(getdate())-month(c_Birth) from from Customers 刚学 为什么from语法错误这句却可行SELECT DATEDIFF(year,c_Birth,GETDATE()) AS 年龄FROM Customers 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 * SQL语句理解 select * from B where (select count(1) as num from A where A.ID = B.ID) = 0select * from B where (select count(1) as num from A where A.ID = B.ID) = 0请问如何理解,为什么 可以在B表中 排除A表的数据 insert into REC_OVER(ORG_ID) select '1' from dual where not exists (select ORG_ID from REC_OVER )insert into REC_OVER(ORG_ID) select '1' from dual where not exists (select ORG_ID from REC_OVER ) 请问oracle里这样的语句,为什么在sql/plus可 在Mysql5.0 中In 用法的疑惑SELECT * FROM A where A.bigclass in(select arrchild from B) 这样子为什么查不到数据,但是写成SELECT * FROM A where A.bigclass in(1,2,35,5) 这样子就可以.注：select arrchild from B 的查询结果 select * from (select * from 表名) 这样的语法中括号里的查询语句是什么意思.为什么不直接from表名select M.* ,case when M.num>1 then M3.Edescs else M3.Edesc end fqtyut,M3.Edesc fpriceut,M4.tradec fcountryfrom (SELECT INVNO,HS 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`