5.Analytical Function.pdf
- 1. Analytical Functions After completing this module, you will be able to: • Enable and Expedite the processing OLAP queries • Describe the Derivation of Ordered Analytical Functions
- 2. Analytical functions „ Support common operation in analytical and data mining environment „ Includes ANSI SQL-99 compliant window functions as well as Teradata-specific functions „ It used in Expression list of SELECT statement
- 3. Aggregate function Lists „ Window aggregate functions „ AVG „ COUNT „ MAX „ MIN „ SUM „ Rank function „ RANK „ Distribution function „ PERCENT_RANK „ Row number function „ ROW_NUMBER „ Teradata-specific functions „ CSUM „ MAVG „ MDIFF „ MLINREG „ MSUM „ QUANTILE „ RANK
- 4. Windows Aggregate Functions Window Feature Ć’ Provides dynamic subset data definition Ć’ ANSI SQL-99 Compliant Window Clauses Entire partition following the current row UNBOUNDED FOLLOWING Entire partition preceding the current row UNBOUNDED PRECEDING starting point for the aggregation group within the Partition. ROWS Grouping of rows based on column specified PARTITION BY arguments that define how values are grouped, ordered. OVER Description Syntax Element
- 5. Computation types ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING Group „ ROWS UNBOUNDED PRECEDING „ ROWS BETWEEN UNBOUNDED PRECEDING AND value PRECEDING „ ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW „ ROWS BETWEEN UNBOUNDED PRECEDING AND value FOLLOWING Cumulative Syntax options Computation
- 6. Computation types contd.. „ ROWS BETWEEN value PRECEDING AND UNBOUNDED FOLLOWING „ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING „ ROWS BETWEEN value FOLLOWING AND UNBOUNDED FOLLOWING Remaining „ ROWS value PRECEDING „ ROWS CURRENT ROW „ ROWS BETWEEN value PRECEDING AND value PRECEDING „ ROWS BETWEEN value PRECEDING AND CURRENT ROW „ ROWS BETWEEN value PRECEDING AND value FOLLOWING „ ROWS BETWEEN CURRENT ROW AND CURRENT ROW „ ROWS BETWEEN CURRENT ROW AND value FOLLOWING „ ROWS BETWEEN value FOLLOWING AND value FOLLOWING Moving Syntax options Computation
- 7. Analytical functions select state, zip_code , Balance_Forward, SUM(Balance_Forward) OVER( PARTITION BY Zip_Code ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) FROM AU.accounts; • SUM • Result State Zip_Code Balance_F Grouped Sum(Balance_Forward CA 90020 5003.8 16950545.29 CA 90020 2582.3 16950545.29 CA 90066 1849.26 14484617.91 CA 90066 8392.2 14484617.91 CA 90066 9948.5 14484617.91
- 8. Analytical functions select state, zip_code , Balance_Forward, SUM(Balance_Forward) OVER( PARTITION BY State order by Zip_Code ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) FROM AU.accounts; • AVG • Result State Zip_Code Balance_Forward Moving Avg(Balance_Forward) CA 90020 18419.5 18420 CA 90020 7571.97 12996 CA 90020 2265.76 9419 CA 90020 2707.29 4182 CA 90020 17572.4 7515 CA 90020 5160.96 8480
- 9. Analytical functions select Account_number, Trans_number , Trans_amount, MIN(Trans_Amount) OVER( PARTITION BY Account_number ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) FROM AU.Trans •MIN • Result Account_Number Trans_Number Trans_amount Cumulative Max(Trans_Amount) 20025236 1235 94.42 94.42 20025236 11235 102 94.42 20025237 1236 -94.5 -94.5 20025237 21455 106 -94.5 20025237 22458 252 -94.5 20025238 1237 -94.57 -94.57 20025239 1238 -94.65 -94.65 20025239 12238 103 -94.65
- 10. Analytical functions select Account_number, Trans_number , Trans_amount, MAX(Trans_Amount) OVER( PARTITION BY Account_number ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) FROM AU.Trans • MAX • Result Account_Number Trans_Number Trans_amount Cumulative Max(Trans_Amount) 20025236 1235 94.42 102 20025236 11235 102 102 20025237 1236 -94.5 252 20025237 21455 106 252 20025237 22458 252 252 20025238 1237 -94.57 -94.57 20025239 1238 -94.65 103 20025239 12238 103 103
- 11. RANK Function „ Returns the rank (1 … n) of all the rows in the group by the value of sort_expression_list, with the same sort_expression values receiving the same rank. „ It is Teradata Extension to ANSI „ Window Aggregate need to use for ANSI SQL-99 select Account_number, Trans_Amount, RANK(Trans_Amount) from AU.Trans select Account_number, Trans_Amount, RANK() OVER(ORDER BY TRANS_AMOUNT DESC) from AU.Trans •Teradata Extn. •ANSI SQL-99 Account_Number Trans_Amount Rank(Trans_Amount) 20033997 2044 1 20033987 2042 2 20033977 2040 3 20033967 2038 4 20033957 2036 5
- 12. PERCENT RANK Function „ Returns the relative rank of rows for a value_expression. „ SQL-99 window function. Select Account_number, Trans_Amount, PERCENT_RANK() OVER(ORDER BY TRANS_AMOUNT DESC) from AU.Trans Account_Number Trans_Amount Percent Rank(Trans_Amount) 20033997 2044 0.000000 20033987 2042 0.000067 20033977 2040 0.000133 20033967 2038 0.000200 20033957 2036 0.000267
- 13. ROW NUMBER Function „ Returns the sequential row number, where the first row is number one, of the row within its window partition according to the window ordering of the window. „ SQL-99 window function. Account_Number Trans_Amount Row Number() 20033997 2044 1 20033987 2042 2 20033977 2040 3 20033967 2038 4 20033957 2036 5 select Account_number, Trans_Amount, ROW_NUMBER() OVER(ORDER BY TRANS_AMOUNT DESC) from AU.Trans
- 14. CSUM Function „ Returns the cumulative (or running) sum of a column expression, assuming the rows are sorted by sort_expression_list. „ Teradata-specific function. select Account_number, Trans_Amount, CSUM(Trans_Amount, Account_number desc) from au.Trans Account_Number Trans_Amount CSum(Trans_Amount,1) 20034000 -764.45 -764.45 20033999 -764.37 -1528.82 20033999 833 -695.82 20033998 -764.3 -1460.12 20033997 -764.22 -2224.34 20033997 2044 -180.34
- 15. MAVG Function „ Returns the moving difference between the current row-column value and the preceding nth row-column value. „ Teradata-specific function. select Account_number, Trans_Amount, MAVG(Trans_Amount, 2, Account_number desc) from au.Trans Account_Number Trans_Amount mount,2,Account_Number DESC) 20034000 -764.45 -764 20033999 -764.37 -764 20033999 833 34 20033998 -764.3 34 20033997 -764.22 -764 20033997 2044 640
- 16. MDIFF Function „ Computes the moving average of a column using the current row and the preceding width-1 rows. „ Teradata-specific function. select Account_number, Trans_Amount, MDIFF(Trans_Amount, 1, Account_number desc) from au.Trans Account_Number Trans_Amount mount,1,Account_Number DESC) 20034000 -764.45 ? 20033999 -764.37 0.08 20033999 833 1597.37 20033998 -764.3 -1597.30 20033997 -764.22 0.08 20033997 2044 2808.22
- 17. MSUM Function „ Computes the moving sum of a column using the current row and the preceding n-1 rows. This function is very similar to the MAVG function. „ Teradata-specific function. select Account_number, Trans_Amount, MSUM(Trans_Amount, 1, Account_number desc) from au.Trans Account_Number Trans_Amount mount,1,Account_Number DESC) 20034000 -764.45 -764.45 20033999 -764.37 -764.37 20033999 833 833.00 20033998 -764.3 -764.30 20033997 -764.22 -764.22 20033997 2044 2044.00
- 18. QUANTILE Function „ Computes the moving sum of a column using the current row and the preceding n-1 rows. This function is very similar to the MAVG function. „ Teradata-specific function. select Account_number, Trans_Amount, QUANTILE(1000, Trans_Amount ASC) from au.Trans Account_Number Trans_AmountQuantile(1000,Trans_Amount ASC) 20033985 -763.3 999 20033984 -763.23 999 20033983 -763.15 999 20033997 -764.22 999 20033975 -762.54 998 20033982 -763.07 998 20033980 -762.92 998