Database Management Systemlab_ppt

8/8/2019 Database Management Systemlab_ppt

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Database Management System

Oracle 8.x


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Data TypesChar( size) : max( 255 character)

:Padded with spaces

Varchar(size): max(2000 char)

:not padded

Number(p,s): p=38 digits

s=125 zeros

Date: DD-MON-YY

Long: variable length char string up to 2GB

(Substring cannot be applied)

RAW:picture or images upto 255 bytes

LONGRAW: 2GB


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Creating a Table

Create table (

Column name1 datatye(size),

Column name1 datatye(size));


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E

xampleof

creating table

SQL> create table emp(

Emp_no varchar(10),Emp_name varchar(10));

Table created


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Retrieving data from table

(DML statements)SQL> select *From < table Name>;

SQL> select < attribute list>From < table list>;

SQL> select < attribute list>

From < table list>

Where ;


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Example

SQL> select *from emp;

SQL> select emp_no, ename

From emp;

SQL> select emp_no, ename

From empWhere deptno=5;


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Order By function

Display the record in either ascending

or descending order.

DEFAULT: Ascending


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Continue ..Select < attribute list>

From

Where < condition> (optional)

Order By attribute_name;

Default in ascending order.

Select < attribute list>

From Where < condition> (optional)

Order By attribute_name desc;


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ExampleSQL> select empno,ename

From emp

Where deptno=5

Order by empno;

Default Ascending

SQL> select empno,enameFrom emp

Where deptno=5

Order by empnodesc;


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Delete Operation

SQL> delete from table name;

All record will be deleted.

SQL> delete from table name

Where conditi

on;

Some records will be deleted.


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Example

SQL> delete from emp;

All record will be deleted.

SQL> delete from emp

where deptno=5;

All the employee records who belongs todeptno5 will be deleted.


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Updating the contents of table

SQL> update

set < column name=exp>, < column name=exp>;

All the record will be updated

SQL> update

set < column name=exp>, < column name=exp>

where ;

Some of the records will be updated.


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Alter table StatementsUsed to change the definition of the table

(DDL) Data Defi. Language

SQL> alter table

add( column name datatype(size));

Add new column

SQL> alter table

Modify( column nameNewdatatype(size));

Increase the size ofan column


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Can not do the followings by

Alter Table Statements

1. Change the table name

2. Rename the column

3. Dr op column ( Only in Oracle 8.0)

4. Decrease the size ofcolumn

( ifdata is present)


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Describe Command

To see the description of the tableSQL> describe ;

SQL> desc ;

SQL> desc emp;


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Save and Run the file

SQL> Save ;

Recently executed SQL statements will be saved

with .sql file extension.

SQL> run < file name>

Output with SQL statement.

SQL> @< file name>

Onlyoutput will generate.


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Logical Operat

or

ANDOR

NOT


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AND Operator

SQL> select

from

where condition1 and condition2;

SQL> select empno,ename

from emp

where deptno=5 and salary>5000;


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OROperator

SQL> select

from

where condition1 or condition2;


from empwhere deptno=5or deptno=2 ;


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NOT Operator

SQL> select

from

where NOT( column name

=value);


from empwhere NOT( deptno=5or deptno=2 );


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Range ( Between)

SQL> select < attribute list>

from

where column name between ( range);


from emp

where salary between 1000 and 5000;


from emp

where salary notbetween 1000 and 5000;


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Pattern Matching

(Like)SQL> select

from

where column name like s%;where column name like sa%;

where column name like _s%;

where column name like _s_;


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Example


from emp

where ename likea%;

where ename like as%;

where ename like _a%;

where ename like _a_;


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IN ANDNOT INSQL> select

from

where column name IN(value,);

where column nameNOT IN(value,);


from emp

where ename IN (arun,tarun);where enameNOT IN (arun,tarun);


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Aggregate function

1. SUM

2. AVG

3. MIN

4. MAX

5. COUNT


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Syntax

SQL> select aggregate_fun( column name)

from ;

SQL> select sum(sal) from emp;

SQL> select avg(sal) from emp;

SQL> select min(sal) from emp;

SQL> select max(sal)from emp;

SQL> select count(empno) from emp;

Count the no. ofvalues.


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Group By and Having

Group By ( for making groups)

Having ( condition)


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Group By and Having

SQL> select aggregate_function( column name)

from

group by having ;

SQL> select sum(salary),deptno

from emp

group by deptno

having salary>1000;


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Constraints

1. Column Level

( ifapply on single column)

2. Table Level

( ifapply on more than one column)


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Table Level


empno

varchar(10),deptno number(2),

primary key( empno,deptno));


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Column Level


empno varchar(10) primary key,

ename varchar(10)salary number(10,2)

deptno number(2));


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Additional Constraints

1. NOT NULL

attribute value will not be NULL

2. UNIQUE

attribute value will be unique but at

least one time it will accept null value.


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NOT NULL


empno varchar(10) NOT NULL,

ename varchar(10)

salary number(10,2)

deptno number(2));


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UNIQUE


empno varchar(10) UNIQUE,

ename varchar(10)

salary number(10,2)

deptno number(2));


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Foreign Key



ename varchar(10)

salary number(10,2)

deptno number(2)

foreign key (deptno) references dept(deptno));


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CheckConstraints



ename varchar(10)check(ename like a%),

salary number(10,2),

deptno number(2));

Only ename starting with lettera are allowed.


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Default

Constraints



ename varchar(10),salary number(10,2),

sex varchar(1) default M,

deptno number(2));


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Join Operation

1. Equi-join

2. Cartesian Product/ Cartesian Join


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Cartesian Pr

oduct/

Cartesian

Join

SQL> select *from emp,dept;

Emp(m) dept(n)

m,n are numberofcolumn in emp and dept table.

p,q are numberof records in emp and dept table.

In result m+n numberofcolumns andp*q number

ofrecords .

Database Management Systemlab_ppt

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