Teradata 的rank() 和 row_number() 函数

Teradata数据库中也有和oracle类似的分析函数，功能基本一样。示例如下：

• RANK() 函数

 

SELECT * FROM salestbl ORDER BY 1,2;

storeid     prodid      sales
----------- -------	---------
1001 	    A 		100000.00		
1001 	    C 		60000.00		
1001 	    D 		35000.00		
1001 	    F 		150000.00		
1002 	    A 		40000.00		
1002 	    C 		35000.00		
1002 	    D 		25000.00		
1003 	    A 		30000.00		
1003 	    B 		65000.00		
1003 	    C 		20000.00		
1003 	    D 		50000.00	

 

 

按sales排序，找出top 3的记录。

 

SELECT storeid, prodid, sales, RANK() OVER (ORDER BY sales DESC) AS Rank_Sales
FROM salestbl
QUALIFY rank_sales <= 3;

    storeid  prodid        sales   Rank_Sales
-----------  ------  -----------  -----------
       1001  F         150000.00            1
       1001  A         100000.00            2
       1003  B          65000.00            3

 

 

rank() over (partition by ... order by ... )用法

 

按storeid分组，然后在每个storeid内对sales降序排序。

 

 

SELECT storeid, prodid, sales, RANK()
OVER (PARTITION BY storeid ORDER BY sales DESC)AS Rank_Sales
FROM salestbl
QUALIFY Rank_Sales <= 3
;

 

storeid       prodid    sales          Rank_Sales
-------       -------   ---------      ---------
1001          F         150000         1
1001          A         100000         2
1001          C         60000          3
1002          A         40000          1
1002          C         35000          2
1002          D         25000          3
1003          B         65000          1
1003          D         50000          2
1003          A         30000          3

 

 

找出销售额top3的prodid。

 

SELECT Prodid, Sumsales, RANK( ) OVER (ORDER BY Sumsales DESC) AS "Ranking"
FROM (SELECT prodid, SUM(sales)
      FROM salestbl
      GROUP BY 1) AS dt(Prodid, Sumsales)
QUALIFY Ranking <= 3;

Prodid     Sumsales      Ranking
------  -----------  -----------
A         170000.00            1
F         150000.00            2
C         115000.00            3

 

 

用rank() 按sales降序排序，如果sales相同，则排名相同。

 

SELECT itemid, salesdate, sales, RANK() OVER (ORDER BY sales DESC)
WHERE salesdate BETWEEN DATE '2004-01-01' AND DATE '2004-03-01'

AND itemid = 10
FROM daily_sales_2004;

     itemid   salesdate        sales  Rank(sales)
-----------  ----------  -----------  -----------
         10  2004-01-10       550.00            1
         10  2004-02-17       550.00            1
         10  2004-02-20       450.00            3
         10  2004-02-06       350.00            4
         10  2004-02-27       350.00            4
         10  2004-01-05       350.00            4
         10  2004-01-03       250.00            7
         10  2004-02-03       250.00            7
         10  2004-01-25       200.00            9
         10  2004-01-02       200.00            9
         10  2004-01-21       150.00           11
         10  2004-02-01       150.00           11
         10  2004-01-01       150.00           11
         10  2004-01-31       100.00           14

 

 

• ROW_NUMBER () 函数

 

用row_number() 按sales降序排序时，即使sales相同，排名也不同。

 

SELECT itemid, salesdate, sales, ROW_NUMBER() OVER (ORDER BY sales DESC)
WHERE salesdate BETWEEN DATE '2004-01-01' AND DATE '2004-03-01'
AND itemid = 10
FROM daily_sales_2004;

     itemid   salesdate        sales  Row_Number()
-----------  ----------  -----------  ------------
         10  2004-01-10       550.00             1
         10  2004-02-17       550.00             2
         10  2004-02-20       450.00             3
         10  2004-02-06       350.00             4
         10  2004-02-27       350.00             5
         10  2004-01-05       350.00             6
         10  2004-01-03       250.00             7
         10  2004-02-03       250.00             8
         10  2004-01-25       200.00             9
         10  2004-01-02       200.00            10
         10  2004-01-21       150.00            11
         10  2004-02-01       150.00            12
         10  2004-01-01       150.00            13
         10  2004-01-31       100.00            14