/*------------------------------效率最低
功能：計算min-max兩個整數之間的隨機整數
作者：
日期：20180831
區別：在查詢中嵌入count(*)計算記錄總條數，效率最低
*/
--SET STATISTICS IO ON; 
SET STATISTICS TIME ON; 
GO 
DECLARE @min INT= 1;
DECLARE @max INT= 100;
DECLARE @icount INT= 0;
DECLARE @t TABLE
    (
     i INT IDENTITY
           PRIMARY KEY
    ,n INT
    );
INSERT  INTO @t
        (n
        )
        SELECT  FLOOR(RAND(CHECKSUM(NEWID())) * ( @max - @min + 1 )) + @min--計算min-max之間的隨機整數
        FROM    master..spt_values AS a
                CROSS JOIN master..spt_values AS b;

                             
SELECT  n
       ,COUNT(n) AS 數量
       ,( SELECT    COUNT(*)
          FROM      @t
        ) AS 總數
       ,COUNT(n) * 100.0 / ( SELECT COUNT(*)
                             FROM   @t
                           ) AS [占比例%]
FROM    @t
GROUP BY n;


/*------------------------------效率居中
功能：計算min-max兩個整數之間的隨機整數
作者：
日期：20180831
區別：提前計算記錄總條數賦值到變量，效率居中
*/
--SET STATISTICS IO ON; 
SET STATISTICS TIME ON; 
GO 
DECLARE @min INT= 1;
DECLARE @max INT= 100;
DECLARE @icount INT= 0;
DECLARE @t TABLE
    (
     i INT IDENTITY
           PRIMARY KEY
    ,n INT
    );
INSERT  INTO @t
        ( n
        )
        SELECT  FLOOR(RAND(CHECKSUM(NEWID())) * ( @max - @min + 1 )) + @min--計算min-max之間的隨機整數
        FROM    master..spt_values AS a
                CROSS JOIN master..spt_values AS b;
SELECT  @icount = COUNT(*)
FROM    @t;
                             
SELECT  n
       ,COUNT(n) AS 數量
       ,@icount AS 總數
       ,COUNT(n) * 100.0 / @icount AS [占比例%]
FROM    @t
GROUP BY n;
/*------------------------------效率最高
功能：計算min-max兩個整數之間的隨機整數
作者：
日期：20180831
區別：根據@@rowcount計算記錄總條數，效率最高
*/
--SET STATISTICS IO ON; 
SET STATISTICS TIME ON; 
GO 
DECLARE @min INT= 1;
DECLARE @max INT= 100;
DECLARE @icount INT= 0;
DECLARE @t TABLE
    (
     i INT IDENTITY
           PRIMARY KEY
    ,n INT
    );
INSERT  INTO @t
        (n
        )
        SELECT  FLOOR(RAND(CHECKSUM(NEWID())) * ( @max - @min + 1 )) + @min--計算min-max之間的隨機整數
        FROM    master..spt_values AS a
                CROSS JOIN master..spt_values AS b;
SET @icount = @@ROWCOUNT; 
--SET @icount=@@IDENTITY                     
SELECT  n
       ,COUNT(n) AS 數量
       ,@icount AS 總數
       ,COUNT(n) * 100.0 / @icount AS [占比例%]
FROM    @t
GROUP BY n;

計算min-max兩個整數之間的隨機整數