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数据库编译中的As和on代表啥

SQL数据库中SELECT AS中的AS代表的是重命名列名或者表名。 其用法是 SELECT 列名1 AS 列1,列名2 AS 列1 FROM 表1 语句表示的意思是从表1中读取列名1和列名2的数据,并且为列名1和列名2分别重命名为列1和列2.

Inner join 内连接 as 别名 on 之后跟内连接的条件 这句话应该是: SELECT column_name(s) FROM table_name1 INNER JOIN table_name2 AS t2 (别名) ON table_name1.column_name=t2.column_name

as不是给表里的字段取别名,而是给查询的结果字段取别名。其目的是让查询的结果展现更符合人们观看习惯,在多张表查询的时候可以直接的区别多张表的同名的字段。 比如: 1、selec name as “姓名” ,sex as "性别" from user 2、select u.name as “...

join on 就是表连接. select * from table1 as t1 join table2 as t2 on(t1.a= t2.b) where t1.c = x order by t1.d desc; 等价于 select * from table 1 as t1 ,table2 as t2 where t1.a = t2.b and t1.c = x order by t1.d desc; 2个SQL语句对...

as time goes by 随着时间的流逝,意味着回顾过去的一种延续状态 as time goes on 随着时间在流逝,意味着从过去到现在、甚至到将来的一种延续状态 as time goes by 随着时间的流逝,意味着回顾过去的一种延续状态 as time goes on 随着时间在流逝,...

upon是“接近,在上面”的意思,是介词, on 和opon一样,as soon as是“一···就”的意思是连词 on和upon是后面加doing或名词 as soon as 后面加句子,不能加单个词 as soon as 和upon 区别 as soon as 和upon 的区别是: as soon as 尽快 / 立即 / 马上 ...

1、as a whole 整体来看; 普遍说来, 一般地说 例句: Is this true just in this country, or in the world as a whole? 只是在这个国家如此呢,还是就整个世界来看都这样? 2、on the whole 大体上,基本上,总的来看[说]; 大抵; 大致如此; 大...

可以换On arriving home, I phoned my mother .= As soon as I arrived home, I phoned my mother. ( 一到家,我就给妈妈打了电话.)On hearing the bell, the students ran into the classroom.=As soon as the they heard the bell, the student...

一般不会用as quick as possible,因为这是一个状语,quick是形容词,是用来修饰名词的,一般用到尽可能快作状语的主句,都是一个动作,所以soon是一个副词,可以修饰动词或形容词。as soon as possible= as quickly as possible,简写ASAC(书...

1 select classname ,manager ,studentname,birthdate,idcard from classinfo join studentinfo on classinfo.classid=studentinfo.classid where classinfo.classid=15 order by studentinfo.birthdate DESC 2 select classname,count(studenti...

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