select A,B,C,D=(select count(*) from 表 where c=a.a and b=a.b) from 表 a请问上面语句where c=a.a and b=a.b) from 表 a 中的a,b,c代表什么呢?

select c.*,d* from ( select 图号 from ( SELECT a.*,b.存货编码 FROM 未明图号 as a left OUTER JOIN 存select c.*,d* from ( select 图号 from (SELECT a.*,b.存货编码FROM 未明图号 as a left OUTER JOIN 存货档案 as bON a.图号=b.规 一个SQL语言,关于ANY 和ALL Q1:SELECT a FROM R WHERE b>= ANY (SELECT d FROM S WHERE c>10);Q2:SELECT a FROM R WHERE b>= ALL(SELECT d FROM S WHERE c>10);(A) Q1和Q2产生的结果一样; (B) Q1的结果总是包含Q2的结果;(C) Q2的结果总是 根据SQL:select a.a,a.b,a.c,b.c,b.d,b.f from a LEFT OUT JOIN b ON a.a = b.c写出右外连接 select A,B,C,D=(select count(*) from 表 where c=a.a and b=a.b) from 表 a请问上面语句where c=a.a and b=a.b) from 表 a 中的a,b,c代表什么呢? delphi 中出现cannot perform this operation on a closed dataset问题procedure Tfrm_bmxx.FormShow(Sender:TObject);begindata1.ADOQYbmxx.Active:=false;with data1.ADOQYbmxx dobeginclose;sql.Clear;sql.text := 'select * from 部门表'; // sql.Add('sele 这段文字的意思update student　　set grade = (　　select grade from　　(　　select id,　　case when score> 90 then 'a'　　when score > 80 then 'b'　　when score > 70 then 'c'　　else 'd' end grade　　from student　　) a select a from dbo.A where c=1 intersect selcet b from dbo.B where d=1求它的行个数怎么附加count函数 ---Why was the offical meeting called?---____new officers.A.Select B.Selecting C.To Select D.For Selecting请问答案应该是哪个?为什么要选那个答案呢? select A from B where C=‘D’and E=‘F’ 如果 F=null 则把E='F' 换成 M='N'select A from B where C=‘D’and M=‘N’ 求写成一个select语句 用的是DB2数据库 C和E都是主keyselect A from B where C=‘D’and E=nvl(‘F’,E) and 58.Mary had no trouble _____ her career because she had always wanted to be a doctor.a.to select b.select c.selecting d.selected如何如何解释 这句sql语句怎么改成left join的select 表2.a as a,表2.a as b,表2.a as c from 表1 a,表2 b,表2 c,表3 dwhere a.条件（+）=b.条件and a.条件（+）=c.条件and d.条件（+）=c.条件可能写错了,应该是这样的,抱歉select 这句sql语句怎么改成left join的select 表2.a as a,表2.a as b,表3.a as c from 表1 a,表2 b,表2 c,表3 dwhere a.条件（+）=b.条件and a.条件（+）=c.条件and d.条件（+）=c.条件可能写错了,应该是这样的,抱歉select sql中left join from 多个表怎么写select * from a,b,c,d LEFT JOIN e on e.id=a.id left join f on f.id=c.id现在这句是错的,怎么写才正确 为什么?The boss is considering _______ an employee who he considers _______ qualified to further study abroad.A.to select,being B.selecting,being C.to select,to be D.selecting,to be select * from a union select * from b 能详细说下么 大量的left join 怎么优化select a.id,a.num,b.num,b.pcs,c.num,c.pcs,d.num,d.pcs,e.num,e.pcs,a.x,a.y from a left join b.id=a.id and b.time=a.timeleft join c.id=a.id and b.time=a.timeleft join d.id=a.id and b.time=a.timeleft join e.id=a.id and b.t If you had to ______ between staying here alone or going with me,what would you do?a、arrange b、 differ c、 select d、 choose单选 下列变量名中正确的是（ ）.A．3S B．Print C．Select My Name D．Select_1 外加为什么啊