Single Row Functions
Objectives
•
Explain the various types of functions
available in SQL.
•
•
Identify the basic concepts of using functions.
•
Explain the conversion functions and how they
might be used.
Include a variety of character, number, and
data functions in SELECT statements.
3-2
Overview of Functions in SQL
Use functions to
•
•
•
•
•
Perform calculations on data.
Modify individual data items.
Manipulate output for groups of rows.
Alter date formats for display.
Convert column datatypes.
3-3
Two Types of SQL Functions
•
Single row functions
– Character
– Number
– Date
– Conversion
•
SINGLE
ROW
Multiple row functions
– Group
3-4
FUNCTION
MULTI
ROW
Single Row Functions: Syntax
Single row functions
•
•
•
•
•
•
Manipulate data items.
Accept arguments and return one value.
Act on each row returned.
Return one result per row.
Modify the datatype.
Can be nested.
Syntax
function_name (column|expression, [arg1, arg2,...])
3-5
Character Functions
• LOWER
• UPPER
• INITCAP
• CONCAT
• SUBSTR
• LENGTH
3-6
Converts to lowercase
Converts to uppercase
Converts to initial capitalization
Concatenates values
Returns substring
Returns number of characters
Example Using Character Functions
Display the fist name and last name of all employees
with the last name of Patel.
SELECT
first_name, last_name
FROM
s_emp
WHERE
last_name = 'PATEL';
no rows returned
SELECT
FROM
WHERE
first_name, last_name
s_emp
UPPER(last_name) = 'PATEL';
FIRST_NAME
-------------------Vikram
Radha
3-7
LAST_NAME
-------------------Patel
Patel
Number Functions
•
•
•
3-8
ROUND
Rounds value to specified decimal
TRUNC
Truncates value to specified decimal
MOD
Returns remainder of division
Conversion Functions: Overview
•
TO_CHAR converts a number or date string to a
character string.
•
TO_NUMBER converts a character string
containing digits to a number.
•
TO_DATE converts a character string of a date to a
date value.
•
Conversion functions can use a format model
composed of many elements.
3-9
Nesting Single Row Functions
•
•
Single row functions can be nested to any level.
Nested functions are evaluated from deepest level
to the least deep level.
F3(F2(F1(col,arg1),arg2),arg3)
Step 1 = Result 1
Step 2 = Result 2
Step 3 = Result 3
3-10