Database

1. Chapter 5
Single-Row Function(1)

2. Objectives
 Understand the usage of functions in
SELECT statements
 Using Number and Text functions

3. What is Function?
 A function is a type of procedure or routine
that performs a specific task.
 A function can receive argument and
always returns a value.
Sorting function
F
T
G
A
R
A
F
G
R
T

4. Two Types of SQL Functions
Functions
Single-row
functions
Multiple-row
functions

5. Single-Row Functions
 Manipulate data items
 Accept arguments and return one value
 Act on each row returned
 Return one result per row
 Can modify the data type
 Can be nested

6. Single-Row Functions
Single-row
functions
Number Text Date Conversion
This chapter Chapter 6

7. Calling a Function in SQL
function_name Is the name of the
function
column Is any named
database column
expression Is any character
string or calculated
expression
arg1, arg2 Is any argument to be
used by the function
function_name (column|expression, [arg1, arg2,...])

8. Number Functions
Function name Description
Round (column/expression,
precision)
Round to a specified
precision
Mod
Example: ( x mod y)
Remainder after
division
Note: There are lots of other Number functions but the one highlights in the course
is more useful

9. Using ROUND Function
(a) Round Function
SELECT Round(5.255,0) as [Round to 0],
Round(5.255,1) as [Round to 1],
Round(5.255,2) as [Round to 2]
FROM test;
Output:
Round to 0 Round to 1 Round to 2
5 5.3 5.26

10. Using Mod Function
It will return the remainder of a division.
SELECT 10 mod 3 As [Mod]
FROM test;
Output:
Mod
1

11. Text Functions
Text
functions
UCase
LCase
StrConv
Case conversion
functions
String manipulation
functions
Mid
Trim
Len
Instr
Left / Right

12. Case Conversion Functions
Functions name Description
UCase (column/expression)
or
StrConv(column/expression, 1)
Puts all the letters in uppercase
LCase (column/expression)
or
StrConv(column/expression, 2)
Puts all the letters in lower case
StrConv(column/expression, 3) Capitalizes the first letter of each
word and puts all the other letters
in lowercase.

13. Using UCase & LCase
SELECT Ucase('smith') AS UpperCase,
Lcase('SMITH') As LowerCase
FROM test;
Output:
UpperCase LowerCase
SMITH smith

14. Using StrConv
SELECT StrConv('my name',1) as [UpperCase],
StrConv('my name',2) as [LowerCase],
StrConv('my name',3) as [Initial]
FROM test;
Output:
UpperCase LowerCase Initial
MY NAME my name My Name

15. Example of Case conversion
SELECT Ucase (CourseDesp) as [Course Name]
FROM Course;
Output:
Course Name
DIPLOMA IN COMPUTER STUDIES
DIPLOMA IN GAMING AND ANIMATION TECHNIQUES
DIPLOMA IN COMPUTING
DIPLOMA IN INFO-COMM TECHNOLOGY
DIPLOMA IN INFORMATION TECHNOLOGY
DIPLOMA IN NETWORK AND CYBERSECURITY

16. String Manipulation Functions
 Perform operations of string such as
creating a substring
 Extract a portion of the string to create a
new character string output
 These functions are useful when you want
to lookup certain data /values from a
particular string.

17. String Manipulation Functions
Functions Name Description
Mid (stringexpression, start, length) Returns part of a string.
Instr(start, stringexpression, search_string) Finds the occurrence of
some search-string pattern
Left(stringexpression, n)
Or
Right(stringexpression, n)
Returns a portion of a
string starting either left or
right.
Trim(stringexpression) Removes blanks spaces
from both sides of a string
Len(stringexpression) Returns the length of a
string

18. MID Function
Mid (stringexpression, start, length)
 Stringexpression
 The field or the value that will be use for the function
to manipulate.
 Start
 Tells Access where in the stringexpression to start
retrieving from
 Length
 The number of characters to extract. If the length is
absent, then function will returns the rest of the string
from where you start.

19. Example on MID function
Output:
Middle of String Rest of String
Computer Computer Studies
Gaming a Gaming and Animation Techniques
Computin Computing
Info-Com Info-Comm Technology
Informat Information Technology
Network Network and CyberSecurity
SELECT Mid(CourseDesp,12,8) As [Middle of String],
Mid(CourseDesp,12) As [Rest of String]
FROM course;

20. INSTR Function
Instr (start, stringexpression, search_string)
 Start
 Specify the position from which Access will start
reading the stringexpression.
 Stringexpression
 The field or the value that will be use for searching.
 Search_string
 The value or the pattern that you looking for in the
stringexpression

21. Example on INSTR Function
Output:
CourseDesp Position of C
Diploma In Computer Studies 12
Diploma in Gaming and Animation
Techniques
35
Diploma In Computing 12
Diploma In Info-Comm Technology 17
Diploma In Information Technology 26
Diploma in Network and CyberSecurity 24
SELECT CourseDesp, Instr(1,CourseDesp,'C')
As [Position of C]
FROM course;

22. LEFT / RIGHT Function
Left (stringexpression, n)
Or
Right (stringexpression, n)
 Stringexpression
 The field or the value that will be use for
manipulate.
 n
 The number of characters that will be
returned from the stringexpression.

23. Example on LEFT/RIGHT function
SELECT MentorName, Left(MentorName,3) As
[Left], Right(MentorName,3) As [Right]
FROM Mentor;
Output
MentorName
Left Right
Goile Goi ile
Rimes Rim mes
Christopher Chr her
Schubert Sch ert
Norman Nor man
Carroll Car oll

24. TRIM Function
Trim (stringexpression)
 Stringexpression
 The field or the value that spaces need to be
removed

25. Example on TRIM function
SELECT TRIM(‘ Hello ’) As [Greetings] ….
Output:
Greetings
Hello

26. LEN Function
Len (stringexpression)
 Stringexpression
 The field or the value that the length to be
calculate.

27. Example on LEN Function
SELECT MentorName, Len(MentorName) As [Length]
FROM Mentor;
Output:
MentorName
Length
Goile 5
Rimes 5
Christopher 11
Schubert 8
Norman 6
Carroll 7

28. Using String Functions
SELECT Mid(FirstName,1,Instr(1,FirstName,' ')) & ', ' &
left(lastname,1) AS [Name]
FROM Student;
Output:
Name
Joseph , B
Laura , K
Choy , L
Derrick , L
Arthur , L
Kathleen , M
………

29. Summary
 Must know the features of Single-Row
functions.
 Usage of both Text and Number
functions.