Interactive SQL and Advance SQL SQL Performance Tuning.pptx

Mrs. Ujjwala S Patil (SITCOE Yadrav) 1
Interactive SQL and Advance SQL: SQL Performance
Tuning
Inbuilt Functions: String, Arithmetic(Numeric
Functions)
Functions are sub programs which are written for a particular
purpose or a task.
Types of Functions:
1. Inbuilt functions
2. User defined functions.

String Functions:
String functions are used to perform an operation on input string
and return an output string.
Arithmetic Function (Numeric Functions):
Numeric Functions are used to perform operations on numbers
and return numbers.

Arithmetic Function (Numeric Functions):
Numeric Functions are used to perform operations on numbers
and return numbers.

Date and Time Functions:
In SQL, dates are complicated since while working with a database,
the format of the date in the table must be matched with the input
date in order to insert. In various scenarios instead of date, datetime
(time is also involved with date) is used.

Aggregate Functions:
An aggregate function performs a calculation on a set of
values, and returns a single value. Except for COUNT(*),
aggregate functions ignore null values. Aggregate functions
are often used with the GROUP BY clause of the SELECT
statement.
• AVG()
• COUNT()
• FIRST()
• LAST()
• MAX()
• MIN()
• SUM()

3.3 Queries using Group by, Having, and Order by
clause, Joins- Inner and Outer Join, Sub Queries.
Employee Table:

Queries using Group by:
The GROUP BY Statement in SQL is used to arrange identical
data into groups with the help of some functions. i.e if a particular
column has same values in different rows then it will arrange these
rows in a group.
Important Points:
GROUP BY clause is used with the SELECT statement.
In the query, GROUP BY clause is placed after the WHERE
clause.
In the query, GROUP BY clause is placed before ORDER BY
clause if used any.

Syntax for Group by clause:
SELECT column1, function_name(column2)
FROM table_name
WHERE condition
GROUP BY column1, column2;
function_name: Name of the function used for example, SUM() ,
AVG().
table_name: Name of the table.
condition: Condition used.

Example:
SELECT NAME, SUM(SALARY) FROM Employee
GROUP BY NAME;
Output:

3.3 Queries using Having clause:
We can use HAVING clause to place conditions to decide which
group will be the part of final result-set. Also we can not use the
aggregate functions like SUM(), COUNT() etc. with WHERE
clause. So we have to use HAVING clause if we want to use any of
these functions in the conditions.

Syntax for Having clause:
SELECT column1, function_name(column2)
FROM table_name
WHERE condition
GROUP BY column1, column2
HAVING condition;
function_name: Name of the function used for example, SUM() ,
AVG().
table_name: Name of the table.
condition: Condition used.

Example:
SELECT NAME, SUM(SALARY) FROM Employee
GROUP BY NAME
HAVING SUM(SALARY)>3000;
Output:

3.3 Queries using Order by clause:
The ORDER BY statement in sql is used to sort the fetched data in
either ascending or descending according to one or more columns.
By default ORDER BY sorts the data in ascending order.
We can use the keyword DESC to sort the data in descending order
and the keyword ASC to sort in ascending order.
To sort in ascending or descending order we can use the keywords
ASC or DESC respectively.
Syntax:
SELECT * FROM table_name ORDER BY column_name ASC|
DESC

Example:

SELECT * FROM Student ORDER BY ROLL_NO DESC;
Output:
ROLL_NO NAME ADDRESS PHONE Age
8 NIRAJ ALIPUR XXXXXXXXXX 19
7 ROHIT BALURGHAT XXXXXXXXXX 18
6 DHANRAJ BARABAJAR XXXXXXXXXX 20
5 SAPTARHI KOLKATA XXXXXXXXXX 19
4 DEEP RAMNAGAR XXXXXXXXXX 18
3 RIYANKA SILIGURI XXXXXXXXXX 20
2 PRATIK BIHAR XXXXXXXXXX 19
1 HARSH DELHI XXXXXXXXXX 18

Joins- Inner and Outer Join:
A SQL Join statement is used to combine data or rows from two or
more tables based on a common field between them. Different
types of Joins are:
•INNER JOIN
•LEFT JOIN
•RIGHT JOIN
•FULL JOIN

Inner Join:
The INNER JOIN keyword selects all rows from both the tables as
long as the condition satisfies. This keyword will create the result-
set by combining all rows from both the tables where the condition
satisfies i.e value of the common field will be same.

Inner Join Syntax:
SELECT table1.column1,table1.column2,table2.column1,....
FROM table1
INNER JOIN table2
ON table1.matching_column = table2.matching_column;
table1: First table.
table2: Second table
matching_column: Column common to both the tables.

Student Table: StudentCourse Table:

Example:
SELECT StudentCourse.COURSE_ID, Student.NAME,
Student.AGE FROM StudentINNER JOIN StudentCourseON
Student.ROLL_NO = StudentCourse.ROLL_NO;
Output:

Left Join (Left Outer Join):
This join returns all the rows of the table on the left side of the join
and matching rows for the table on the right side of join. The rows
for which there is no matching row on right side, the result-set will
contain null. LEFT JOIN is also known as LEFT OUTER JOIN.

Syntax :
SELECT table1.column1,table1.column2,table2.column1,....
FROM table1 LEFT JOIN table2
matching_column: Column common to both the tables

Example for Left outer Join:
SELECT Student.NAME, StudentCourse.COURSE_ID
FROM Student
LEFT JOIN StudentCourse
ON StudentCourse.ROLL_NO = Student.ROLL_NO;
Output:

RIGHT JOIN (RIGHT OUTER JOIN) :
RIGHT JOIN is similar to LEFT JOIN. This join returns
all the rows of the table on the right side of the join and
matching rows for the table on the left side of join. The
rows for which there is no matching row on left side, the
result-set will contain null. RIGHT JOIN is also known
as RIGHT OUTER JOIN.

Syntax for Right Outer Join:
SELECT able1.column1,table1.column2,table2.column1,....
FROM table1
RIGHT JOIN table2
matching_column: Column common to both the tables

Example for Right Outer Join:
SELECT Student.NAME, Student Course.COURSE_ID FROM
Student
RIGHT JOIN StudentCourse
ON StudentCourse.ROLL_NO = Student.ROLL_NO;
Output:

FULL JOIN :
FULL JOIN creates the result-set by combining result of both
LEFT JOIN and RIGHT JOIN. The result-set will contain all the
rows from both the tables. The rows for which there is no
matching, the result-set will contain NULL values.

Syntax for full Outer Join:
SELECT table1.column1,table1.column2,table2.column1,...
FROM table1
FULL JOIN table2
matching_column: Column common to both the tables.

Example of Full Join:
SELECT Student.NAME,StudentCourse.COURSE_ID FROM
StudentFULL JOIN StudentCourse ON StudentCourse.ROLL_NO
= Student.ROLL_NO;
Output:

Sub Query:
In SQL a Subquery can be simply defined as a query within
another query. In other words we can say that a Subquery is a
query that is embedded in WHERE clause of another SQL query.
Syntax:
There is not any general syntax for Subqueries. However,
Subqueries are seen to be used most frequently with SELECT
statement as shown below:
SELECT column_name FROM table_name WHERE
column_name expression operator ( SELECT
COLUMN_NAME from TABLE_NAME WHERE ... );

Important rules for Subqueries:
• Subqueries can be used with SELECT, UPDATE, INSERT, DELETE
statements along with expression operator. It could be equality
operator or comparison operator such as =, >, =, <= and Like
operator.
• A subquery is a query within another query. The outer query is called
as main query and inner query is called as subquery.
• The subquery generally executes first, and its output is used to
complete the query condition for the main or outer query.
• Subquery must be enclosed in parentheses.
• Subqueries are on the right side of the comparison operator.
• ORDER BY command cannot be used in a Subquery. GROUPBY
command can be used to perform same function as ORDER BY
command.
• Use single-row operators with singlerow Subqueries. Use multiple-
row operators with multiple-row Subqueries.

Example:
Database :
Student :
NAME ROLL_NO LOCATION PHONE_NUMBER
Ram 101 Chennai 9988775566
Raj 102 Coimbatore 8877665544
Sasi 103 Madurai 7766553344
Ravi 104 Salem 8989898989
Sumathi 105 Kanchipuram 8989856868
NAME ROLL_NO SECTION
Ravi 104 A
Sumathi 105 B
Raj 102 A

To display NAME, LOCATION, PHONE_NUMBER of the
students from DATABASE table whose section is A
Select NAME, LOCATION, PHONE_NUMBER
from DATABASE WHERE ROLL_NO
IN (SELECT ROLL_NO from STUDENT where SECTION=’A’);
Output:
NAME ROLL_NO LOCATION PHONE_NUMBER
Ravi 104 Salem 8989898989
Raj 102 Coimbatore 8877665544

3.4 Views: Concept of View, The create view
Command, Updating views, Dropping views.
View can be defined as a logical part (marked for some special
purpose) of the total data present in the table.
View can be created with the help of Select statement.
View can be read only or they could be used to insert, update, and
delete the table data and view data.
Views are used for the purpose of data security and minimizing
data redundancy.

Create View:
Database views are created using the CREATE VIEW statement.
Views can be created from a single table, multiple tables or another
view.
Syntax:
CREATE VIEW view_name AS
SELECT column1, column2.....
FROM table_name WHERE [condition];

Example:
CUSTOMERS Table:

CREATE VIEW CUSTOMERS_VIEW AS
SELECT name, age
FROM CUSTOMERS;
Output:
View Created
0.06 seconds

How to Display the View:
SELECT * FROM CUSTOMERS_VIEW;
Output:

Update View:
View can be used to update the data from the table as well as view.
Example:
UPDATE CUSTOMERS_VIEW SET AGE = 35 WHERE name =
'Ramesh';
Output:
One row(s) updated
0.03 seconds

Now we can check the updated data by using Select
statement:
SELECT * FROM CUSTOMERS;
Output:

Dropping View:
Drop view command is used for dropping the view.
Syntax:
Drop vew <View nmae>;
Example:
DROP VIEW CUSTOMERS_VIEW;
Output:
View dropped
0.12 seconds.

3.5 Sequences: Creating Sequence, Altering Sequence,
Dropping Sequence:
"A Sequence is simply an automatic counter, which generates
sequential numbers whenever required.“
A sequence can be defined to:
•Generate numbers in ascending or descending order.
•Provide intervals between numbers.
•Caching of sequence numbers in memory to speed up their
availability .
A sequence is an independent object and can be used with any
table that requires its output.

Creating a Sequences :
The minimum information required for generating numbers using a
sequence is:
• The starting number.
• The maximum number that can be generated by a sequence.
• The increment value for generating the next number.
Syntax:
CREATE SEQUENCE <Sequence Name> [INCREMENT BY
<IntegerValue> START WITH <Integer Value> MAXVALUE
<Integer Value> MINVALUE <Integer Value>
[CYCLE/NOCYCLE] [ CACHE/NOCACHE] ;

INCREMENT BY:
Specifies the interval between sequence numbers. It can be any positive or
negative value but not zero. If this clause is omitted, the default value is 1.
MAXVALUE And MINVALUE :
Specifies the maximum or minmum value that a sequence can generate.
START WITH:
Specifies the first sequence number to be generated.
CYCLE:
Specifies that the sequence continues to generate repeat values after reaching
either its maximum value.
CACHE:
Specifies how many values to generate in advance and to keep in memory for
faster access.Minimum value is two for this option.

Example for Creating Sequence:
Create sequence stud_seq
incremented by 1
Start with 100
Maxvalue 10000
Minvalue 100
Cycle cache 7;
Output:
Sequence created
0.04 seconds.

After creating a sequence we can access its value with the help
of nextval and currval
Nextval:
This returns original value of the sequence.
Example:
Select stud_seq.nextval from dual;
Output: NEXTVAL
100
1 row(s) returned in 0.02 seconds.

Currval:
This returns the current value of the sequence which is next value
to the next value.
Example:
Select stud_seq.currval from dual;
Output: CURRVAL
101
1 row(s) returned in 0.02 seconds.

Altering a Sequence :
A sequence once created can be altered. This is achieved by
using the ALTER SEQUENCE statement.
The START value of the sequence cannot be altered .
Syntax:
ALTER SEQUENCE <SequenceName> [INCREMENT BY
<IntegerValue> MINVALUE <IntegerValue> ];
Example:
Alter sequence stud_seq maxval 2000;
Output:
Sequence altered
0.02 seconds

Dropping Sequence:
Sequence can be delete or dropped using drop sequence
command.
Syntax:
Drop sequence <Sequence_Name>;
Example:
Drop sequence stud_seq;
Output:
Sequence dropped
0.02 seconds

3.6- Indexes- Index Types, creating of an Index,
Simple, Unique and Composite Index, Dropping
Indexes.
An index helps to speed up SELECT queries and
WHERE clauses, but it slows down data input, with
the UPDATE and the INSERT statements. Indexes can be created
or dropped with no effect on the data.
Types of Index:
1. Simple Index
2. Composite Index
3. Unique index.

Create Simple Index:
When we create index on single column of the table, it is called as
simple index.
Syntax:
CREATE INDEX index_name
ON table_name (column1);
Example:
CREATE INDEX stud_Indx
ON Student (Roll_No);
Output:
Index created
0.12 seconds

Create Composite Index:
When we create index on multiple columns of the table, it is called
as Composite index.
Syntax:
CREATE INDEX index_name
ON table_name (column1, Column2,…);
Example:
CREATE INDEX stud_Indx
ON Student (Roll_No, Name);
Output:
Index created
0.12 seconds

Create Unique Index:
When we create index on single column or multiple columns by
using “Unique” Keywordof the table, it is called Unique index.
Syntax:
CREATE UNIQUE INDEX index_name
ON table_name (column1);
Example:
CREATE UNIQUE INDEX stud_Indx
ON Student (Roll_No);
Output:
Index created
0.12 seconds

Dropping Index:
Index can be dropped using drop index command.
Syntax:
Drop Index Index_name;
Example:
Drop index stud_indx;
Output:
Index dropped
0.12 seconds.

3.7 Synonyms: Creating Synonyms, Dropping
Synonyms:
A synonym is an alternative name for objects such as tables,
views, sequences, stored procedures, and other database objects.
You generally use synonyms when you are granting access to an
object from another schema and you don't want the users to have to
worry about knowing which schema owns the object.

Creating Synonyms:
To create the synonyms create synonym command is used.
Syntax:
Create Synonym synonym_Name For Object_Name;
Example:
Create synonym sit_stud for student;
Output:
Synonym created
1.02 seconds

Dropping Synonyms:
A synonym can be deleted or dropped by using drop synonym
command
Syntax:
Drop synonym synonym_Name;
Example:
Drop synonym sit_stud;
Output:
Synonym dropped
1.02 seconds

Thank You

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