Question

所以我有表名报告详细信息

No(autoincrement)       Code       Stats(bool)
--------------------------------------
       1                 F01        0
       2                 F02        0
       3                 F03        0
       4                 F03        1
       5                 F03        1
       6                 F04        1
       7                 F04        0

所以场景是如果代码有stats的值为true然后显示它们全部，如果代码没有值true则只显示false所以我想要的结果是（注意：一个代码总是有1个值为false的记录）

No(autoincrement)           Code       Stats
--------------------------------------------
           1                  F01        0
           2                  F02        0
           4                  F03        1
           5                  F03        1
           6                  F04        1

因为f01和f02没有值stats为true然后显示它们以及对于案例f03和f04因为stat值为true显示它们全部为true并忽略false值

那么我的查询如何得到结果

Answer 1

您似乎想要DENSE_RANK()功能

select * from
(
    select *,
            dense_rank() over (partition by Code order by Stats desc) Seq
    from table t
) t
where Seq = 1

如果您不想使用subquery表单，可以通过SQL Server中提供的 TOP with ties 来探索上述内容

select top 1 with ties [No(autoincrement)], Code, [Stats(bool)]
from table t
order by dense_rank() over (partition by Code order by [Stats(bool)] desc)

由于MySQL没有分析功能。因此，您可以通过UNION ALL

探索这些内容

select * 
from table t
where exists (
    select 1 from table
    where autoincrement  = t.autoincrement  and Stats = 1
) UNION ALL 
select * 
from table t
where not exists (
    select 1 from table
    where code = t.code and Stats = 1) 
ORDER BY 1

Answer 2

SELECT No,Code,Stats FROM
(SELECT No,Code,Stats,
  Case when @Code = t.Code Then
            Case when @stats != t.stats  Then
                 @DenseRank := @DenseRank + 1
            ELSE
                 @DenseRank := 1
            END
   Else
      @DenseRank := 1 
   END as DenseRank,
  @Code :=t.code as VarCode,
  @stats :=t.stats as varstatus
  FROM Table1 t join
  (Select @DenseRank := 1,@Code := '',@stats := '' )r
Order BY CODE,Stats DESC)
AS T1
WHERE
DenseRank=1
Order BY CODE,Stats DESC;

输出

No  Code    Stats
1   F01     0
2   F02     0
4   F03     1
5   F03     1
6   F04     1

演示

http://sqlfiddle.com/#!9/f868a/3

查询boolean和if语句

2 个答案: