我现在有数据库方面的两张表,要查询出每个用户的某个月出勤的情况怎么弄...答:Create table userinfo(id number(8,0) ,username varchar2(32),u_id number(8,0))Create table checkinfo(id number(8,0), checktype varchar2(32),u_id number(8,0) )这两句是创建两个数据表userinfo,checkinfo。具体查询语句如下 select userinfo.username,m.出勤,n.事假,p.病假...
T-sql查询语句。。。假如数据库有如下一张表 Id A B 1 0 2 1 3_百 ...答:创建表 create table t(id int,a int,b int)insert into t values (1,0,2)insert into t values (1,3,0)insert into t values (1,1,0)insert into t values (2,0,0)insert into t values (2,1,0)insert into t values (3,2,2)insert into t values (3,2,1)执行:select ...