Question

我有这种格式的数据：

CREATE TABLE data(y int)

INSERT INTO data VALUES ((1))
INSERT INTO data VALUES ((55555))
INSERT INTO data VALUES ((55555))
INSERT INTO data VALUES ((99999))

我想创建一个直方图，以便大致了解我的数据的分布情况。我正在考虑将此格式作为输出：

lowerBoundary upperBoundary y
------------- ------------- -----------
0             9999          1
10000         19999         0
20000         29999         0
30000         39999         0
40000         49999         0
50000         59999         2
60000         69999         0
70000         79999         0
80000         89999         0
90000         99999         1

Answer 1

您必须创建一个数字表，以便正确显示0 - 行。然后你可以计算每个“组”的下边界和上边界。

示例SQL：

SELECT lowerBoundary, upperBoundary, COUNT(d.y) AS y
FROM (

    SELECT n*10000 AS lowerBoundary, (n+1)*10000-1 AS upperBoundary
    FROM (

        -- Selects possible groups. Make this big enough for your data.
        SELECT ones.n + 10*tens.n + 100*hundreds.n AS n
        FROM (VALUES(0),(1),(2),(3),(4),(5),(6),(7),(8),(9)) ones(n),
             (VALUES(0),(1),(2),(3),(4),(5),(6),(7),(8),(9)) tens(n),
             (VALUES(0),(1),(2),(3),(4),(5),(6),(7),(8),(9)) hundreds(n)
    ) numbersTable
) boundaries

-- join with data
LEFT JOIN data d
ON d.y BETWEEN lowerBoundary AND upperBoundary

-- avoid trailing '0' rows
WHERE lowerBoundary <= (SELECT MAX(d.y) FROM data d)
GROUP BY lowerBoundary, upperBoundary
ORDER BY 1

Click here to run this skript at SQL-Fiddle

Answer 2

另一种选择......

我使用TVF生成动态范围。作为单一语句功能，它非常快。此外，如果您不能使用UDF，逻辑很容易移植到cte或子查询中。

Select RetVal1
      ,RetVaL2
      ,y = sum(case when y is null then 0 else 1 end)
 From [dbo].[udf-Range-Number-Span](0,100000,10000) A
 Left Join Data B on y>=RetVal1 and y<RetVal2
 Group By RetVal1,RetVal2

<强>返回

RetVal1     RetVaL2     y
0.00        10000.00    1
10000.00    20000.00    0
20000.00    30000.00    0
30000.00    40000.00    0
40000.00    50000.00    0
50000.00    60000.00    2
60000.00    70000.00    0
70000.00    80000.00    0
80000.00    90000.00    0
90000.00    100000.00   1

UDF（如果需要）

CREATE FUNCTION [dbo].[udf-Range-Number-Span] (@R1 money,@R2 money,@Incr money)
Returns Table
Return (
    with cte0(M) As (Select cast((@R2-@R1)/@Incr as int)),
         cte1(N) As (Select 1 From (Values(1),(1),(1),(1),(1),(1),(1),(1),(1),(1)) N(N)),
         cte2(N) As (Select Top (Select M from cte0) Row_Number() over (Order By (Select NULL)) From cte1 a,cte1 b,cte1 c,cte1 d,cte1 e,cte1 f,cte1 g,cte1 h )

    Select RetSeq=1,RetVal1=@R1,RetVal2=@R1+@Incr 
    Union All 
    Select N+1,(N*@Incr)+@R1,((N*@Incr)+@R1)+@Incr 
    From   cte2,cte0 
    Where  N<cte0.M
)
--Max 100 million observations 
--Select * from [dbo].[udf-Range-Number-Span](1,4,.5)

选择数据，分组为直方图

2 个答案: