SQL Keywords and Functions.pptx

SQL keywords and Functions
By: Ms. Rubab
Rubab.itc@suk-iba.edu.pk
IBA ITC Sobhodero
Managed By Khairpur Campus,
IBA Sukkur University
By: Ms. Rubab For DIT

The SQL ORDER BY Keyword
• The ORDER BY keyword is used to sort the result-set in
ascending or descending order.
• The ORDER BY keyword sorts the records in ascending
order by default. To sort the records in descending
order, use the DESC keyword.
ORDER BY Syntax
SELECT column1, column2, ...
FROM table_name
ORDER BY column1, column2, ... ASC|DESC;

Example
SELECT * FROM students
ORDER BY address ASC;
The above query selects all the students from student
table and sorts them in ascending order by their address
ORDER BY address DESC;
table and sorts them in descending order by their address
SELECT * FROM Customers
ORDER BY address ASC, Name DESC;
table and sorts them in ascending order by their address
and descending order by their names

SQL NULL Values
A field with a NULL value is a field with no value.
If a field in a table is optional, it is possible to insert a
new record or update a record without adding a value to
this field. Then, the field will be saved with a NULL value.
Note: A NULL value is different from a zero value or a
field that contains spaces. A field with a NULL value is
one that has been left blank during record creation!

How to test Null values
It is not possible to test for NULL values with comparison
operators, such as =, <, or <>.
We will have to use the IS NULL and IS NOT
NULL operators instead.
Syntax:
SELECT column_name(s)
FROM table_name
WHERE column_name IS NULL;
The IS NULL operator is used to test for empty values
(NULL values).

IS NOT Null Syntax
SELECT column_names
FROM table_name
WHERE column_name IS NOT NULL;
The IS NOT NULL operator is used to test for non-empty
values (NOT NULL values).
Example:
Where address IS NOT NULL;

SQL AS Keyword
The AS command is used to rename a column or table
with an alias.
NOTE:An alias only exists for the duration of the query.
Syntax:
SELECT column_name AS Alias, column2 AS Alias
FROM table_name
WHERE condition

Example
SELECT fees AS STUDENT_FEES FROM students

The SQL SELECT TOP Clause
The SELECT TOP clause is used to specify the number of
records to return.
The SELECT TOP clause is useful on large tables with
thousands of records. Returning a large number of
records can impact performance.
Syntax:
SELECT column_name(s)
FROM table_name
WHERE condition
LIMIT number;

Example
SELECT ID,NAME
FROM students
WHERE ID<26
LIMIT 10
The above query selects top 10 records from
students table where id is less than 26
SELECT * FROM students.
LIMIT 3;

SQL MIN() and MAX() Functions
The MIN() function returns the smallest value of the
selected column.
The MAX() function returns the largest value of the
selected column.
Min Syntax:
SELECT MIN(column_name)
FROM table_name
WHERE condition;
Max Syntax:
SELECT Max(column_name)
FROM table_name
WHERE condition;

Examples
SELECT MIN(fees)
FROM students;
SELECT MAX(fees)
FROM students;

SQL COUNT(), AVG() and
SUM() Functions
More SQL Functions

SQL COUNT () Function
The COUNT() function returns the number of rows that
matches a specified criterion
Syntax:
SELECT COUNT(column_name)
FROM table_name
WHERE condition;
Example:
SELECT COUNT(ID)
FROM stuents;

SQL AVG() Function
The AVG() function returns the average value of a
numeric column.
Syntax:
SELECT AVG(column_name)
FROM table_name
WHERE condition;
Example:
SELECT AVG(fees)
FROM students;

SQL SUM() Function
The SUM() function returns the total sum of a numeric
column.
SELECT SUM(column_name)
FROM table_name
WHERE condition;
Example:
SELECT SUM(fees)
FROM students;

SQL Keywords and Functions.pptx

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