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将4列的值显示成一列指定名字的表select ( prefix||' ' ||first||' ' || last||' ' || suffix) as title from namesSELECTconcat_ws(' ', prefix,first,last,suffix)AS title FROMnames;

package UserManager; /** * Created by mff on 2017/5/15. */import java.sql.*;public class MysqlConnect { public static Connection connectMysql() { // 驱动程序名 // String driver = "

题目：For this challenge you need to create a simple SELECT statement that will return all columns from the people table, and join to the sales table so that you can return the COUNT of all sales and R

1.交叉连接查询返回两个或多个表所有数据行的笛卡儿积，没有where子句select* from store,stuff;2.内连接查询普通的连接类型，而且是最匀称的，添加where子句select 列名 from 表1，表2 where 表1.列名1=表2.列名2select 列名 from 表1 inner join 表2 on 表1.列名1=表2.列名2；sele

select Sname from student where Sno IN (select Sno from SC group by Sno //根据Sno分组，统计每个学生选修了几门课程。如果等于course的总数，就是我们要找的Sno having count(*) = (select count(*) from course )) //统