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