Oracle: Functions

1. 1 Using ORACLE® Using functions (single row and aggregate functions) And the ‘GROUP BY ‘ clause

2. 2 FUNCTIONS We have many functions in Oracle that can be used to perform a myriad of tasks. There are two types of functions viz: Functions take input ,process it and provide the output. Single row functions operate only on one row (1 input and 1 output) Aggregate functions can operate on a range of rows ( multiple inputs and one output)

3. 3 FUNCTIONS Single row functions can be divided into different parts as: Character Single row functions Number General Conversion Date

4. 4 CHARACTER FUNCTIONS Case manipulation functions Character manipulation functions

5. 5 CHARACTER FUNCTIONS SELECTprod_ID, INITCAP (prod_name) , CONCAT ('Rs ',prod_cost) AS COST FROM product_master WHERE prod_name LIKE( LOWER ('TEAK%')); SELECTprod_ID, UPPER (prod_name) , CONCAT ('Rs ',prod_cost) AS COST FROM product_master WHERE prod_name LIKE ( CONCAT ( '%', SUBSTR ( 'teak_sofa', 6, 4 ))); Equivalent to LIKE ( ‘%sofa’);

6. 6 NUMBER FUNCTIONS SELECT ROUND (3.14126,4), TRUNC (3.14126,4) , MOD ( 22, 7 ) FROM DUAL ; (DUAL is a dummy table in Oracle used to perform calculations.) SELECTprod_ID , prod_name , ROUND( MOD (prod_stock,prod_order),0) AS REORDER_LVL FROM product_master ORDER BY REORDER_LVL; (Here we use the alias name to order the output)

7. 7 DATE FUNCTIONS We can use either MONTH or YEAR as parameters in the ROUND and TRUNC functions.

8. 8 DATE MANIPULATIONS Apart from the date functions we can also perform arithmetic operations on dates as:. Adding or subtracting a number to or from a date to get a resultant date. Subtracting two dates to find the number of days between those dates. Adding hours to a date by dividing the number of hours by 24. SELECT SYSDATEASTODAY, (SYSDATE+1) AS NEXT_DAY, (SYSDATE-1) AS PREV_DAY FROM DUAL;

9. 9 CONVERSION FUNCTIONS Here in the TO_NUMBER function we are converting the string ‘2000’ to a number 2000. In TO_DATE we have to specify the format of the output date and In TO_CHAR we have to specify the format of input date to be converted to a string

10. 10 GENERAL FUNCTIONS SELECT prod_ID, prod_name, NVL (prod_order,0), NVL2 (prod_sales,'YES','NO'), NULLIF (prod_stock,(prod_order+prod_sales)) AS NULLIF FROM product_master;

11. 11 AGGREGATE FUNCTIONS Aggregate functions take multiple rows as input and give one output. The SYNTAX is: SELECT column1,column2…….aggregate_function( column)… FROMtable_name WHERE (expression/condition);

12. 12 AGGREGATE FUNCTIONS SELECT COUNT (prod_ID) AS COUNT, MIN (prod_cost) AS MINIMUM, MAX (prod_sales) AS MAXIMUM, AVG (prod_cost) AS AVERAGE, SUM (prod_stock) AS SUM, ROUND( STDDEV (prod_sales),3) AS STD_DEVIAYION, ROUND( VARIANCE (prod_stock),3) AS VARIANCE FROM product_master; (We can also use ‘*’ in COUNT and ‘DISTINCT’ in AVG )

13. 13 GROUP BY CLAUSE When we wish to divide the table into multiple groups based on some criterion we use the ‘GROUP BY’ clause. It is mandatory that while using a group by clause we include the column used in the group must not be used in a aggregate function in the SELECT statement. SYNTAX: SELECT column1,column2…….aggregate_function( column)… FROMtable_name GROUP BY column WHERE (expression/condition); It is mandatory to use the group by clause when displaying any column along with a aggregratefunction.We can also use multiple columns in the group by clause. Use the WHERE clause to furthur filter results.

14. THANK YOU 14 THANK YOU FOR VIEWING THIS PRESENTATION FOR MORE PRESENTATIONS AND VIDEOS ON ORACLE AND DATAMINING , please visit: www.dataminingtools.net