SQL Functions - Oracle SQL Fundamentals
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The document covers SQL fundamentals focusing on functions in Oracle 11g, highlighting single-row functions and their structure. It details character, number, and date functions, including examples of usage and operations such as concatenation and type casting. The document also discusses the NVL and CASE functions, along with records manipulation functions like COUNT, MAX, and MIN.
![Character Functions(cont’d)
•CONCAT(<column_name1>|<expression1>,
(<column_name2>|<expression2>))
equivalent to concatination operator
•SUBSTR(<column_name>|<expression>,M[,N])
returns characters starting from m and ending at n. As n is optional
if it is skipped then by default characters are returned from m to end
of characters.
•LENGTH(<column_name>|<expression>)
returns total no. of characters
8](https://image.slidesharecdn.com/lecture6-180428055748/85/SQL-Functions-Oracle-SQL-Fundamentals-8-320.jpg)
SQL Functions - Oracle SQL Fundamentals
- 1. SQL Fundamentals Oracle 11g M U H A M M A D WA H E E D O R AC L E DATA BA S E D E V E LO P E R E M A I L : m .wa h e e d 3 6 6 8 @ g m a i l . co m Lecture#6 SQL Functions
- 3. SQL Functions(cont’d) Functions are powerful feature of SQL and can be used to do the following: •Perform calculations on data •Modify individual data items •Manipulate output for group of rows •Format dates and numbers for display •Convert column data type 3
- 4. SQL Functions(cont’d) There are following two types of SQL functions: •Single Row Functions Operate on single rows only and return single result per row. •Multiple Row Functions Can be used to manipulate group of rows to generate single result against group of rows and also known as “Group Functions”. *For now, We will consider only single-row functions. 4
- 5. Single-Row Functions There are following types of single-row functions: 5
- 6. Single-Row(cont’d) There are following types of character function: 6
- 7. Character Functions There are following case-manipulation functions: •LOWER(<column_name>|<expression>) converts alpha characters to lowercase •UPPER(<column_name>|<expression>) converts alpha characters to uppercase •INITCAP(<column_name>|<expression>) capitalize the first letter of each word 7
- 8. Character Functions(cont’d) •CONCAT(<column_name1>|<expression1>, (<column_name2>|<expression2>)) equivalent to concatination operator •SUBSTR(<column_name>|<expression>,M[,N]) returns characters starting from m and ending at n. As n is optional if it is skipped then by default characters are returned from m to end of characters. •LENGTH(<column_name>|<expression>) returns total no. of characters 8
- 11. Use of Character Functions 11 •Example: SELECT std_id, CONCAT(std_first_name,std_last_name) AS std_name, LENGTH(std_address), INSTR( std_address, ‘#’) FROM student WHERE SUBSTR(std_name,2,3) = ‘ai’;
- 12. Number Functions 12 •Number functions input as well as output only numeric values.
- 13. Number Functions(cont’d) 13 •Number functions input as well as output only numeric values.
- 14. Number Functions(cont’d) 14 •It can have negative value of ‘n’. •Example: SELECT ROUND(45.926,-1) FROM DUAL; Result: 50 SELECT TRUNC(45.926,-2) FROM DUAL; Result: 0
- 15. Date Functions 15 •For current date we use: SELECT SYSDATE FROM DUAL; Result( standard/default format): 26-APR-18
- 16. Elements of Date Functions 16
- 18. Arithmetic - Date Functions(cont’d) 18
- 19. Use Date Functions(cont’d) 19 •Example: SELECT std_id, (SYSDATE - admission_date)/ 7 AS weeks FROM student;
- 21. Implicit type casting 21 •For assignments, Oracle server can automatically convert following:
- 22. Implicit type casting(cont’d) 22 •For expression, Oracle server can automatically convert following:
- 25. Type casting - Date Functions(cont’d) 25 •Example: i- SELECT std_id, TO_CHAR(admission_date,’MM/YY’) FROM student; ii- SELECT std_id, TO_CHAR(admission_date,’Day Month DD,YYYY’) AS “Admission Date” FROM student; iii- SELECT std_id, TO_CHAR(admission_date,’fmDay Month DD,YYYY’) AS “Admission Date” FROM student;
- 26. Type casting - Date Functions(cont’d) 26 •Example: i- SELECT std_id, TO_DATE(’27-APR-2018,’MM/YY’) FROM student; ii- SELECT std_id, TO_DATE(‘MAY 27,2018’,’fxMonth DD,YYYY’) AS “Admission Date” FROM student;
- 27. Type casting - Date Functions(cont’d) 27 •Example: SELECT std_id, TO_CHAR(admission_date,’ fmDD MONTH,YYYY fmHH12:MI:SS AM’) FROM student; •Result(TO_CHAR): 26 APRIL,2018 2:00:00 PM
- 29. NVL Function 29 •Converts a null value to an actual value •Syntax: NVL(<column/experession>,<value>) •Used with NUMBER,VARCHAR2 and DATE datatypes •Data types must match for actual value - NVL(std_age,0) - NVL(std_address,’Pakistan’) - NVL(std_dob,’01-JAN-00’)
- 30. CASE Function 30 •It provides IF-THEN-ELSE nesting facility in SQL •Syntax:
- 31. CASE Function(cont’d) 31 •Example: SELECT tch_id,tch_name,tch_salary, CASE tch_designation WHEN ‘VISITING’ salary*1.1 WHEN ‘ASSISTANT LECTURER’ salary*1.2 WHEN ‘LECTURER’ salary*1.5 ELSE salary END AS “Revised Salary” FROM teacher; •*Note: same functionality can be performed using DECODE in Oracle. Do it by yourself.
- 32. Records Manipulation Function 32 •There are few such functions: COUNT,MAX,MIN •Example: i- SELECT COUNT(*) FROM student; ii- SELECT MAX(tch_salary) FROM teacher; iii- SELECT MIN(std_dob) FROM student;
- 33. Nested Single-row Functions 33 •Single functions can be nested to any level.
- 34. Nested Single-row Functions 34 •Single functions can be nested to any level. SELECT NVL(TO_CHAR(std_dob,’MON DD,YYYY’),’NO VALUE’) FROM student;
- 35. Feedback/Suggestions? The feedback I get is that my books are honest. - Laurie Halse Anderson