introdution to SQL and SQL functions

INTRODUCTION TO SQL
Mehreen uzma
Roll no 32

Structured Query Language
What is SQL?
SQL is a standard language for accessing
and manipulating databases.
 SQL stands for Structured Query
Language
 SQL lets you access and manipulate
databases
 SQL is an ANSI (American National
Standards Institute) standard
What Can SQL do?
 SQL can execute queries against a
database
 SQL can retrieve data from a database
 SQL can insert records in a database
 SQL can update records in a database
 SQL can delete records from a
database
 SQL can create new databases
 SQL can create new tables in a
database
 SQL can create stored procedures in a
database

SQL is a Standard - BUT....
 Although SQL is an ANSI (American National Standards Institute) standard,
there are different versions of the SQL language.
 However, to be compliant with the ANSI standard, they all support at least
the major commands (such as SELECT, UPDATE, DELETE, INSERT, WHERE)
similar manner.
Using SQL in Your Web Site…
 To build a web site that shows data from a database, you will need:
 An RDBMS database program (i.e. MS Access, SQL Server, MySQl

RDBMS:-
 RDBMS stands for Relational Database Management System.
 RDBMS is the basis for SQL, and for all modern database systems such as MS SQL Server, IBM
DB2, Oracle, MySQL, and Microsoft Access.
 The data in RDBMS is stored in database objects called tables.
 A table is a collection of related data entries and it consists of columns and rows

Sql commands
SQL defines following data languages to manipulate data of RDBMS.
 DDL : Data Definition Language
 DML : Data Manipulation Language
 TCL : Transaction Control Language
 DCL : Data Control Language
 DQL : Data Query Language

Command Description
Create to create new table or database
Alter for alteration
Truncate delete data from table
Drop to drop a table
Rename to rename a table
DDL : Data Definition Language
 All DDL commands are auto-committed. That means it saves all the
changes permanently in the database

Create Command
create is a DDL command used to create a table or a database.
Creating a Database:
Syntax,
 create database database-name;
Example for Creating Database
 create database Test;
The above command will create a
database named Test.
Creating a Table:
Syntax,
 create table table-name
{
column-name1 datatype1,
};
Example for creating Table
 create table Student(id int, name varchar, age int);
The above command will create a new table Student in
database system with 3 columns, namely id, name and
age.

Alter Command
alter command is used for
alteration of table structures.
There are various uses
of alter command, such as,
• to add a column to existing
table
• to rename any existing
column
• to change datatype of any
column or to modify its size.
• alter is also used to drop a
column.

To Add Column to existing Table:
Using alter command we can add a column to an existing table. Following is the Syntax,
alter table table-name add(column-name datatype);
Here is an Example for this,
alter table Student add(address char);
The above command will add a new column address to the Student table
To Add Multiple Column to existing Table:
Using alter command we can even addmultiple columns to an existing table. Followingis the Syntax,
alter table table-name add(column-name1 datatype1, column-name2 datatype2, column-name3
datatype3);
alter table Student add(father-name varchar(60), mother-name varchar(60), dob date);
The above command will add three new columns to the Student table

To Add column with Default Value:
alter command can add a new column to an existing table with default values. Following is the
Syntax,
alter table table-name add(column-name1 datatype1 default data);
alter table Student add(dob date default '1-Jan-99');
The above command will add a new column with default value to the Student table
To Modify an existing Column:
alter command is used to modify data type of an existing column . Following is the Syntax,
alter table table-name modify(column-name datatype);
alter table Student modify(address varchar(30));
The above command will modify address column of the Student table

To Rename a column:
Using alter command you can rename an existing column. Following is the Syntax,
alter table table-name rename old-column-name to column-name;
alter table Student rename address to Location;
The above command will rename address column to Location.
To Drop a Column:
alter command is also used to drop columns also. Following is the Syntax,
alter table table-name drop(column-name);
alter table Student drop(address);
The above command will drop address column from the Student table

SQL queries to Truncate, Drop or Rename a Table
Truncate Command:
truncate command removes all records from a table. But this command will not destroy the table's
structure. When we apply truncate command on a table its Primary key is initialized. Following is
its Syntax,
truncate table table-name
Here is an Example explaining it.
truncate table Student;
The above query will delete all the records of Student table.
truncate command is different from delete command. delete command will delete all the rows
from a table whereas truncate command re-initializes a table(like a newly created table).
For eg. If you have a table with 10 rows and an auto_increment primary key, if you
use delete command to delete all the rows, it will delete all the rows, but will not initialize the
primary key, hence if you will insert any row after using delete command, the auto_increment
primary key will start from 11. But in case of truncatecommand, primary key is re-initialized.

Drop Command:
drop query completely removes a table from database. This command will also destroy the table
structure. Following is its Syntax,
drop table table-name
drop table Student;
The above query will delete the Student table completely. It can also be used on Databases. For
Example, to drop a database,
drop database Test;
The above query will drop a database named Test from the system.
Rename Query:
rename command is used to rename a table. Following is its Syntax,
rename table old-table-name to new-table-name
rename table Student to Student-record;
The above query will rename Student table to Student-record.

DML : Data Manipulation Language
 Data Manipulation Language (DML) statements are used for managing data in
database. DML commands are not auto-committed. It means changes made by
DML command are not permanent to database, it can be rolled back.
Command Description
Insert to insert a new row
Update to update existing row
Delete to delete a row
Merge merging two rows or two tables

1) INSERT command:
Insert command is used to insert data into a table. Following is its general syntax,
INSERT into table-name values(data1,data2,..)
Lets see an example,
Consider a table Student with following fields.
S_id S_Name Age
INSERT into Student values(101,'Adam',15);
The above command will insert a record into Student table.
S_id S_Name age
101 Adam 15

Example to Insert NULL value to a column
Both the statements below will insert NULL value into age column of the Student table.
INSERT into Student(id,name) values(102,'Alex');
Or,
INSERT into Student values(102,'Alex',null);
The above command will insert only two column value other column is set to null.
S_id S_Name Age
101 Adam 15
102 Alex

Example to Insert Default value to a column
INSERT into Student values(103,'Chris',default)
S_id S_Name age
101 Adam 15
102 Alex
103 Chris 14
Suppose the age column of student table has default value of 14.
Also, if you run the below query, it will insert default value into the age column, whatever the default
value may be.
INSERT into Student values(103,'Chris')

2) UPDATE command:
Update command is used to update a row of a table. Following is its general syntax,
UPDATE table-name set column-name = value where condition;
Lets see an example,
update Student set age=18 where s_id=102;
S_id S_Name age
101 Adam 15
102 Alex 18
103 Chris 14
Example to Update multiple columns
UPDATE Student set s_name='Abhi',age=17 where s_id=103;
The above command will update two columns of a record.
S_id S_Name age
101 Adam 15
102 Alex 18
103 Abhi 17

3) Delete command:
Delete command is used to delete data from a table. Delete command can also be used with condition
to delete a particular row.
Following is its general syntax,
DELETE from table-name;
Example to Delete all Records from a Table
DELETE from Student;
The above command will delete all the records from Student table.
Example to Delete a particular Record from a Table
Consider the following Student table
DELETE from Student where s_id=103;
The above command will delete the record where s_id is 103 from Student table.

TCL : Transaction Control Language
Transaction Control Language(TCL) commands are used to manage transactions in database. These are
used to manage the changes made by DML statements. It also allows statements to be grouped
together into logical transactions
These commands are to keep a check on other commands and their affect on the database. These
commands can annul changes made by other commands by rolling back to original state. It can also
make changes permanent.
Command Description
Commit to permanently save
Rollback to undo change
Savepoint to save temporarily

Commit command:
Commit command is used to permanently save any transaaction into database.
Following is Commit command's syntax,
commit;
Rollback command:
This command restores the database to last commited state. It is also use with savepoint command
to jump to a savepoint in a transaction.
Following is Rollback command's syntax,
rollback to savepoint-name;
Savepoint command:
savepoint command is used to temporarily save a transaction so that you can rollback to that point
whenever necessary.
Following is savepoint command's syntax,
savepoint savepoint-name;

DCL : Data Control Language
Data Control Language(DCL) is used to control privilege in Database. To perform any
operation in the database, such as for creating tables, sequences or views we need
privileges. Privileges are of two types,
 System : creating session, table etc are all types of system privilege.
 Object : any command or query to work on tables comes under object privilege
Data control language provides command to grant and take back authority.
Command Description
Grant grant permission of right
Revoke take back permission.

To Allow a User to create Session
grant create session to username;
To Allow a User to create Table
grant create table to username;
To provide User with some Space on Tablespace to store Table
alter user username quota unlimited on system;
To Grant all privilege to a User
grant sysdba to username
To Grant permission to Create any Table
grant create any table to username
To Grant permission to Drop any Table
grant drop any table to username
To take back Permissions
revoke create table from username

WHEREclause
Where clause is used to specify condition while retriving data from table. Where clause is used
mostlywithSelect,UpdateandDeletequery.Ifcondititonspecifiedbywhereclauseistruethenonly
theresultfromtableisreturned.
SyntaxforWHEREclause
SELECTcolumn-name1,
column-name2,
column-name3,
column-nameN
fromtable-nameWHERE[condition];

Example using WHERE clause
Consider a Student table,
s_id s_Name age address
101 Adam 15 Noida
102 Alex 18 Delhi
103 Abhi 17 Rohtak
104 Ankit 22 Panipat
Now we will use a SELECT statement to display data of the table, based on a condition, which we
will add to the SELECT query using WHERE clause.
SELECT s_id,
s_name,
age,
address
from Student WHERE s_id=101;
s_id s_Name age Address
101 Adam 15 Noida

SELECT Query
Select query is used to retrieve data from a tables. It is the most used SQL query. We can retrieve
complete tables, or partial by mentioning conditions using WHERE clause
Syntax of SELECT Query
SELECT column-name1, column-name2, column-name3, column-nameN from table-name;
Example for SELECT Query
Conside the following Student table,
S_id S_Name age Address
101 Adam 15 Noida
102 Alex 18 Delhi
SELECT s_id, s_name, age from Student.
The above query will fetch information of s_id, s_name and age column from Student table
S_id S_Name age
101 Adam 15
102 Alex 18

Order By Clause
Order by clause is used with Select statement for arranging retrieved data in sorted order.
The Order byclause by default sort data in ascending order. To sort data in descending
order DESC keyword is used withOrder by clause.
Syntax of Order By
SELECT column-list from table-name order by asc|desc;
Example using Order by
Consider the following Emp table,
Eid Name Age salary
401 Anu 22 9000
402 Shane 29 8000
403 Rohan 34 6000
404 Scott 44 10000
405 Tiger 35 8000

Example of Order by DESC
Consider the Emp table described above,
SELECT * from Emp order by salary DESC;
The above query will return result in descending order of the salary.
Eid Name age salary
404 Scott 44 10000
401 Anu 22 9000
405 Tiger 35 8000
402 Shane 29 8000
403 Rohan 34 6000

Group By Clause
Group by clause is used to group the results of a SELECT query based on one or more columns. It is
also used with SQL functions to group the result from one or more tables.
Syntax for using Group by in a statement:
SELECT column_name, function(column_name)
FROM table_name
WHERE condition
GROUP BY column_name
Example of Group by in a Statement
Consider the following Emp table.
Eid name age Salary
401 Anu 22 9000
402 Shane 29 8000
403 Rohan 34 6000
404 Scott 44 9000
405 Tiger 35 8000

Here we want to find name and age of employees grouped by their salaries
SQL query for the above requirement will be,
SELECT name, age
from Emp group by salary
Result will be,
Name Age
Rohan 34
Shane 29
Anu 22

HAVING Clause
having clause is used with SQL Queries to give more precise condition for a statement. It is used to
mention condition in Group based SQL functions, just like WHERE clause.
Syntax for having will be,
select column_name, function(column_name)
FROM table_name
WHERE column_name condition
GROUP BY column_name
HAVING function(column_name) condition
Example of HAVING Statement
Consider the following Sale table.
Oid order_name previous_balance Customer
11 ord1 2000 Alex
12 ord2 1000 Adam
13 ord3 2000 Abhi
14 ord4 1000 Adam
15 ord5 2000 Alex

Suppose we want to find the customer whose previous_balance sum is more than 3000.
We will use the below SQL query,
SELECT *
from sale group customer
having sum(previous_balance) > 3000
Result will be,
oid order_name previous_balance Customer
11 ord1 2000 Alex

Distinct keyword
The distinct keyword is used with Select statement to retrieve unique values from the
table. Distinctremoves all the duplicate records while retrieving from database.
Syntax for DISTINCT Keyword
SELECT distinct column-name from table-name;
Example
Consider the following Emp table.
Eid name age Salary
401 Anu 22 5000
402 Shane 29 8000
403 Rohan 34 10000
404 Scott 44 10000
405 Tiger 35 8000

introdution to SQL and SQL functions

AND & OR operator
AND and OR operators are used with Where clause to make more precise conditions for fetching
data from database by combining more than one condition together.
AND operator
AND operator is used to set multiple conditions with Where clause.
Example of AND
Consider the following Emp table
Eid name age salary
401 Anu 22 5000
402 Shane 29 8000
403 Rohan 34 12000
404 Scott 44 10000
405 Tiger 35 9000

SELECT * from Emp WHERE salary < 10000 AND age > 25
The above query will return records where salary is less than 10000 and age greater than 25.
Eid name age Salary
402 Shane 29 8000
405 Tiger 35 9000

OR operator
OR operator is also used to combine multiple conditions with Where clause. The only difference
between AND and OR is their behaviour. When we use AND to combine two or more than two
conditions, records satisfying all the condition will be in the result. But in case of OR, atleast one
condition from the conditions specified must be satisfied by any record to be in the result.
Example of OR
Consider the following Emp table
eid name age salary
401 Anu 22 5000
402 Shane 29 8000
403 Rohan 34 12000
404 Scott 44 10000
405 Tiger 35 9000

SELECT * from Emp WHERE salary > 10000 OR age > 25
The above query will return records where either salary is greater than 10000 or age greater than
25.
402 Shane 29 8000
403 Rohan 34 12000
404 Scott 44 10000
405 Tiger 35 9000

Advance structured query language
Farwa waqar
Roll no 38

SQL Constraints
SQl Constraints are rules used to limit the type of data that can go into a table, to maintain the
accuracy and integrity of the data inside table.
Constraints can be divided into following two types,
 Column level constraints : limits only column data
 Table level constraints : limits whole table data
Constraints are used to make sure that the integrity of data is maintained in the database. Following
are the most used constraints that can be applied to a table.
 NOT NULL
 UNIQUE
 PRIMARY KEY
 FOREIGN KEY
 CHECK
 DEFAULT
NOT NULL Constraint:
NOT NULL constraint restricts a column from having a NULL value. Once NOT NULL constraint is
applied to a column, you cannot pass a null value to that column. It enforces a column to contain a
proper value. One important point to note about NOT NULL constraint is that it cannot be defined
at table level.
Example using NOT NULL constraint
CREATE table Student(s_id int NOT NULL, Name varchar(60), Age int);
The above query will declare that the s_id field of Student table will not take NULL value.

UNIQUE Constraint:
UNIQUE constraint ensures that a field or column will only have unique values. A UNIQUE constraint
field will not have duplicate data. UNIQUE constraint can be applied at column level or table level.
Example using UNIQUE constraint when creating a Table (Table Level)
CREATE table Student(s_id int NOT NULL UNIQUE, Name varchar(60), Age int);
The above query will declare that the s_id field of Student table will only have unique values and
wont take NULL value.
Example using UNIQUE constraint after Table is created (Column Level)
ALTER table Student add UNIQUE(s_id);
The above query specifies that s_id field of Student table will only have unique value.
Primary Key Constraint:
Primary key constraint uniquely identifies each record in a database. A Primary Key must contain
unique value and it must not contain null value. Usually Primary Key is used to index the data inside
the table.
Example using PRIMARY KEY constraint at Table Level
CREATE table Student (s_id int PRIMARY KEY, Name varchar(60) NOT NULL, Age int);
The above command will creates a PRIMARY KEY on the s_id .
Example using PRIMARY KEY constraint at Column Level
ALTER table Student add PRIMARY KEY (s_id);
The above command will creates a PRIMARY KEY on the s_id .

Foreign Key Constraint:
FOREIGN KEY is used to relate two tables. FOREIGN KEY constraint is also used to restrict actions
that would destroy links between tables. To understand FOREIGN KEY, let's see it using two table.
Customer_Detail Table :
c_id Customer_Name address
101 Adam Noida
102 Alex Delhi
103 Stuart Rohtak
Order_Detail Table :
Order_id Order_Name c_id
10 Order1 101
11 Order2 103
12 Order3 102

In Customer_Detail table, c_id is the primary key which is set as foreign key in Order_Detail table.
The value that is entered in c_id which is set as foreign key in Order_Detail table must be present
in Customer_Detail table where it is set as primary key. This prevents invalid data to be inserted
into c_id column of Order_Detailtable.
Example using FOREIGN KEY constraint at Table Level
CREATE table Order_Detail(order_id int PRIMARY KEY,
order_name varchar(60) NOT NULL,
c_id int FOREIGN KEY REFERENCES Customer_Detail(c_id));
In this query, c_id in table Order_Detail is made as foriegn key, which is a reference of c_id column
of Customer_Detail.

CHECK Constraint:
CHECK constraint is used to restrict the value of a column between a range. It performs check on
the values, before storing them into the database. Its like condition checking before saving data into
a column.
Example using CHECK constraint at Table Level
create table Student(s_id int NOT NULL CHECK(s_id > 0),
Name varchar(60) NOT NULL,
Age int);
The above query will restrict the s_id value to be greater than zero.
Example using CHECK constraint at Column Level
ALTER table Student add CHECK(s_id > 0);

SQL Functions
SQL provides many built-in functions to perform operations on data. These functions are useful
while performing mathematical calculations, string concatenations, sub-strings etc. SQL functions
are divided into two catagories,
 Aggregrate Functions
 Scalar Functions
Aggregrate Functions:
These functions return a single value after calculating from a group of values.Following are some
frequently used Aggregrate functions.
1) AVG()
Average returns average value after calculating from values in a numeric column.
Its general Syntax is,
SELECT AVG(column_name) from table_name
Example using AVG()
Consider following Emp table
Eid Name age salary
401 Anu 22 9000
402 Shane 29 8000
403 Rohan 34 6000
404 Scott 44 10000
405 Tiger 35 8000

2) COUNT()
Count returns the number of rows present in the table either based on some condition or without
condition.
Its general Syntax is,
SELECT COUNT(column_name) from table-name
Example using COUNT()
eid Name age Salary
401 Anu 22 9000
402 Shane 29 8000
403 Rohan 34 6000
404 Scott 44 10000
405 Tiger 35 8000
SQL query to count employees,
satisfying specified condition is,
SELECT COUNT(name) from
Emp where salary = 8000;
Result of the above query will
be,
count(name)
2

3) FIRST()
First function returns first value of a selected column
Syntax for FIRST function is,
SELECT FIRST(column_name) from table-name
Example of FIRST()
Eid Name age salary
401 Anu 22 9000
402 Shane 29 8000
403 Rohan 34 6000
404 Scott 44 10000
405 Tiger 35 8000
SQL query
SELECT FIRST(salary) from Emp;
Result will be,
first(salary)
9000

4) LAST()
LAST return the return last value from selected column
Syntax of LAST function is,
SELECT LAST(column_name) from table-name
Example of LAST()
Eid Name age salary
401 Anu 22 9000
402 Shane 29 8000
403 Rohan 34 6000
404 Scott 44 10000
405 Tiger 35 8000
SQL query will be,
SELECT LAST(salary) from emp;
Result of the above query will be,
last(salary)
8000

5) MAX()
MAX function returns maximum value from selected column of the table.
Syntax of MAX function is,
SELECT MAX(column_name) from table-name
Example of MAX()
Eid Name age salary
401 Anu 22 9000
402 Shane 29 8000
403 Rohan 34 6000
404 Scott 44 10000
405 Tiger 35 8000
SQL query to find Maximum salary is,
SELECT MAX(salary) from emp;
Result of the above query will be,
MAX(salary)
10000

6) MIN()
MIN function returns minimum value from a selected column of the table.
Syntax for MIN function is,
SELECT MIN(column_name) from table-name
Example of MIN()
Consider following Emp table,
Eid Name age salary
401 Anu 22 9000
402 Shane 29 8000
403 Rohan 34 6000
404 Scott 44 10000
405 Tiger 35 8000
SQL query to find minimum salary is,
SELECT MIN(salary) from emp;
Result will be,
MIN(salary)
8000

7) SUM()
SUM function returns total sum of a selected columns numeric values.
Syntax for SUM is,
SELECT SUM(column_name) from table-name
Example of SUM()
Eid Name age Salary
401 Anu 22 9000
402 Shane 29 8000
403 Rohan 34 6000
404 Scott 44 10000
405 Tiger 35 8000
SQL query to find sum of salaries will be,
SELECT SUM(salary) from emp;
Result of above query is,
SUM(salary)
41000

Scalar Functions
Scalar functions return a single value from an input value. Following are soe frequently used Scalar
Functions.
1) UCASE()
UCASE function is used to convert value of string column to Uppercase character.
Syntax of UCASE,
SELECT UCASE(column_name) from table-name
Example of UCASE()
Eid Name age Salary
401 Anu 22 9000
402 Shane 29 8000
403 Rohan 34 6000
404 Scott 44 10000
405 Tiger 35 8000

SQL query for using UCASE is,
SELECT UCASE(name) from emp;
Result is,
UCASE(name)
ANU
SHANE
ROHAN
SCOTT
TIGER

2) LCASE()
LCASE function is used to convert value of string column to Lowecase character.
Syntax for LCASE is,
SELECT LCASE(column_name) from table-name
Example of LCASE()
Eid Name Age salary
401 Anu 22 9000
402 shane 29 8000
403 rohan 34 6000
404 scott 44 10000
405 Tiger 35 8000

SQL query for converting string value to Lower case is,
SELECT LCASE(name) from emp;
Result will be,
LCASE(name)
Anu
Shane
Rohan
Scott
Tiger

3) MID()
MID function is used to extract substrings from column values of string type in a table.
Syntax for MID function is,
SELECT MID(column_name, start, length) from table-name
Example of MID()
Eid name age Salary
401 Anu 22 9000
402 shane 29 8000
403 rohan 34 6000
404 scott 44 10000
405 Tiger 35 8000

SQL query will be,
select MID(name,2,2) from emp;
Result will come out to be,
MID(name,2,2)
Nu
Ha
Oh
Co
Ig

4) ROUND()
ROUND function is used to round a numeric field to number of nearest integer. It is used on Decimal
point values. Syntax of Round function is,
SELECT ROUND(column_name, decimals) from table-name
Example of ROUND()
eid name age Salary
401 Anu 22 9000.67
402 shane 29 8000.98
403 rohan 34 6000.45
404 Scott 44 10000
405 Tiger 35 8000.01

SQL query is,
SELECT ROUND(salary) from emp;
Result will be,
ROUND(salary)
9001
8001
6000
10000
8000

Join in SQL
SQL Join is used to fetch data from two or more tables, which is joined to appear as single set of
data. SQL Join is used for combining column from two or more tables by using values common to
both tables. Join Keyword is used in SQL queries for joining two or more tables. Minimum
required condition for joining table, is (n-1) where n, is number of tables. A table can also join to
itself known as, Self Join.
Types of Join
The following are the types of JOIN that we can use in SQL.
 Inner
 Outer
 Left
 Right

Cross JOIN or Cartesian Product
This type of JOIN returns the cartesian product of rows from the tables in Join. It will return
table which consists of records which combines each row from the first table with each row
of the second table.
Cross JOIN Syntax is,
SELECT column-name-list
from table-name1
CROSS JOIN
table-name2;
Example of Cross JOIN
The class table,
ID NAME
1 Abhi
2 Adam
4 Alex
The class_info table,
ID Address
1 DELHI
2 MUMBAI
3 CHENNAI

Cross JOIN query will be,
SELECT *
from class,
cross JOIN class_info;
The result table will look like,
ID NAME ID Address
1 Abhi 1 DELHI
2 Adam 1 DELHI
4 Alex 1 DELHI
1 Abhi 2 MUMBAI
2 adam 2 MUMBAI
4 Alex 2 MUMBAI
1 abhi 3 CHENNAI
2 adam 3 CHENNAI
4 Alex 3 CHENNAI

INNER Join or EQUI Join
This is a simple JOIN in which the result is based on matched data as per the
equality condition specified in the query.
Inner Join Syntax is,
from table-name1
INNER JOIN
table-name2
WHERE table-name1.column-name = table-name2.column-name;
Example of Inner JOIN
The class table,
ID NAME
1 abhi
2 adam
3 alex
4 anu
ID Address
1 DELHI
2 MUMBAI
3 CHENNAI

Inner JOIN query will be,
SELECT * from class, class_info where class.id = class_info.id;
ID NAME ID Address
1 abhi 1 DELHI
2 adam 2 MUMBAI
3 Alex 3 CHENNAI

Natural JOIN
Natural Join is a type of Inner join which is based on column having same name and
same datatype present in both the tables to be joined.
Natural Join Syntax is,
SELECT *
from table-name1
NATURAL JOIN
table-name2;
Example of Natural JOIN
The class table,
ID NAME
1 Abhi
2 adam
3 alex
4 anu
ID Address
1 DELHI
2 MUMBAI
3 CHENNAI

Natural join query will be,
SELECT * from class NATURAL JOIN class_info;
ID NAME Address
1 abhi DELHI
2 adam MUMBAI
3 alex CHENNAI
In the above example, both the tables being joined have ID
column(same name and same datatype), hence the records for
value of ID matches in both the tables will be the result of Natural
of these two tables

Outer JOIN
Outer Join is based on both matched and unmatched data. Outer Joins
subdivide further into,
• Left Outer Join
• Right Outer Join
• Full Outer Join
Left Outer Join
The left outer join returns a result table with the matched data of two
then remaining rows of the lefttable and null for the right table's column.
Left Outer Join syntax is,
from table-name1
LEFT OUTER JOIN
table-name2
on table-name1.column-name = table-name2.column-name;

Example of Left Outer Join
The class table,
ID NAME
1 abhi
2 adam
3 alex
4 anu
5 ashish
ID Address
1 DELHI
2 MUMBAI
3 CHENNAI
7 NOIDA
8 PANIPAT
Left Outer Join query will be,
SELECT * FROM class LEFT OUTER JOIN class_info ON (class.id=class_info.id);
ID NAME ID Address
1 abhi 1 DELHI
2 adam 2 MUMBAI
3 Alex 3 CHENNAI
4 Anu null null
5 Ashish null null

Right Outer Join
The right outer join returns a result table with the matched data of two tables then
remaining rows of the right table and null for the left table's columns.
Right Outer Join Syntax is,
select column-name-list
from table-name1
RIGHT OUTER JOIN
table-name2

Example of Right Outer Join
The class table,
ID NAME
1 abhi
2 adam
3 alex
4 anu
5 ashish
ID Address
1 DELHI
2 MUMBAI
3 CHENNAI
7 NOIDA
8 PANIPAT
Right Outer Join query will be,
SELECT * FROM class RIGHT OUTER JOIN class_info on (class.id=class_info.id);
ID NAME ID Address
1 abhi 1 DELHI
2 adam 2 MUMBAI
3 alex 3 CHENNAI
Null null 7 NOIDA
Null null 8 PANIPAT

Full Outer Join
The full outer join returns a result table with the matched data of two table
then remaining rows of both lefttable and then the right table.
Full Outer Join Syntax is,
select column-name-list
from table-name1
FULL OUTER JOIN
table-name2
Example of Full outer join is,
The class table,
ID NAME
1 abhi
2 adam
3 alex
4 anu
5 ashish

ID Address
1 DELHI
2 MUMBAI
3 CHENNAI
7 NOIDA
8 PANIPAT
Full Outer Join query will be like,
SELECT * FROM class FULL OUTER JOIN class_info on
(class.id=class_info.id);
ID NAME ID Address
1 abhi 1 DELHI
2 adam 2 MUMBAI
3 Alex 3 CHENNAI
4 Anu null null
5 ashish null null
Null Null 7 NOIDA
Null Null 8 PANIPAT

Set Operation in SQL
SQL supports few Set operations to be performed on table data. These are used to get meaningful
results from data, under different special conditions.
Union
UNION is used to combine the results of two or more Select statements. However it will eliminate
duplicate rows from its result set. In case of union, number of columns and datatype must be same
in both the tables.
Example of UNION
The First table,
ID Name
1 abhi
2 adam
The Second table,
ID Name
2 adam
3 Chester

Union SQL query will be,
select * from First
UNION
select * from second
ID NAME
1 abhi
2 adam
3 Chester

Union All
This operation is similar to Union. But it also shows the duplicate rows.
Example of Union All
The First table,
ID NAME
1 Abhi
2 Adam
The Second table,
ID NAME
2 Adam
3 Chester

Union All query will be like,
select * from First
UNION ALL
ID NAME
1 abhi
2 adam
2 adam
3 Chester

Intersect
Intersect operation is used to combine two SELECT statements, but it only retuns the records which
are common from both SELECT statements. In case of Intersect the number of columns and
datatype must be same. MySQL does not support INTERSECT operator.
Example of Intersect
The First table,
ID NAME
1 Abhi
2 Adam
The Second table,
ID NAME
2 Adam
3 Chester

Intersect query will be,
select * from First
INTERSECT
The result table will look like
ID NAME
2 adam

Minus
Minus operation combines result of two Select statements and return only those result which
belongs to first set of result. MySQL does not support INTERSECT operator.
Example of Minus
The First table,
ID NAME
1 abhi
2 adam
The Second table,
ID NAME
2 adam
3 Chester

Minus query will be,
select * from First
MINUS
ID NAME
1 Abhi

introdution to SQL and SQL functions

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introdution to SQL and SQL functions