Question

我可以在不创建新表的情况下将表上的值与sql上的相同值进行比较 sql output selisih意味着价值和nilai之间的差异意味着价值

Create table tblData(
  nourut int,
  nama varchar(50),
  nilai int
);
Create table tblData1(
  nourut int,
  nama varchar(50),
  nilai int
);
insert into tblData values
(1,"Yuanita Prabandini Soesilo",85),
(2,"Marco Anthonius Pareira",80),
(3,"William Jaya Dwipangga",95);
insert into tblData1 values
(1,"Yuanita Prabandini Soesilo",85),
(2,"Marco Anthonius Pareira",80),
(3,"William Jaya Dwipangga",95);
select tblData.nama as namamhs,
tblData.nilai,
tblData1.nama,
tblData1.nilai,
case
when(tblData.nilai-tblData1.nilai<0)
then (tblData.nilai-tblData1.nilai)*-1
when(tblData.nilai-tblData1.nilai>=0)
then (tblData.nilai-tblData1.nilai)
end as selisih
from tblData,tblData1
where tblData1.nama<>tblData.nama
order by tblData1.nama DESC;

我创建了两个tblData，以便比较哪种方法无法在不创建新表的情况下比较同一个表上的值？

Answer 1

只需要一个表，在FROM子句中，您为每个表提供一个Alias，这样您就可以将表引入查询两次：

select t1.nama as namamhs,
t1.nilai,
t2.nama,
t2.nilai,
case
when(t1.nilai-t2.nilai<0)
then (t1.nilai-t2.nilai)*-1
when(t1.nilai-t2.nilai>=0)
then (t1.nilai-t2.nilai)
end as selisih
from tblData as t1, tblData as t2
where t1.nama<>t2.nama
order by t2.nama DESC;

Answer 2

是的，您可以使用JOIN来ALIAS使用自己的表格。

SELECT
  d1.nama as namamhs,
  d1.nilai,
  d2.nama,
  d2.nilai,
  CASE
    WHEN (d1.nilai - d2.nilai < 0)
      THEN (d1.nilai - d2.nilai) * -1
    WHEN (d1.nilai - d2.nilai >= 0)
      THEN (d1.nilai - d2.nilai)
  END AS selisih
FROM tblData d1
INNER JOIN tblData d2 ON d1.nama <> d2.nama
ORDER BY d2.nama DESC;

Answer 3

你可以试试这个：

select 
  a.nama,
  a.nilai,
  b.nama,
  b.nilai,
  abs(a.nilai-b.nilai) 
from tbldata as a ,tbldata as b
where a.nama<>b.nama
order by b.nama desc

sql比较同一个表上的值

3 个答案: