Database Management System 1

Database Lab 2
Swapnali Pawar
Swapnali Pawar

The SQL CREATE DATABASE Statement
The CREATE DATABASE statement is used to create
a new SQL database.
Syntax
CREATE DATABASE databasename;
Make sure you have admin privilege before creating any
database. Once a database is created, you can check it in the
list of databases with the following SQL command:
SHOW DATABASES;
DATABASE
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The SQL DROP DATABASE
Statement
The DROP DATABASE statement is used to
drop an existing SQL database.
Syntax
DROP DATABASE databasename;
Note: Be careful before dropping a database. Deleting a
database will result in loss of complete information stored in
the database!
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A. Tables
1.Basic Data Types-
char,varchar,varchar2,long,number,fixed
2.Commands to Create Table-
create table
3.Commands to Handle Tables-
Alter
Drop
Insert
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1.Basic Data Types-
• Each column in a database table is required to have a
name and a data type.
• An SQL developer must decide what type of data that
will be stored inside each column when creating a table.
• The data type is a guideline for SQL to understand what
type of data is expected inside of each column, and it
also identifies how SQL will interact with the stored
data.
Note: Data types might have different names in different
database. And even if the name is the same, the size and
other details may be different! Always check the
documentation!
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In MySQL there are three main data types:
1.String 2.numeric 3.date and time.
1.String Datatype
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2. Numeric Datatypes
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3. date and time
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2.Commands to Create Table-
The CREATE TABLE statement is used to create a new table in a
database.
Syntax
CREATE TABLE table_name (
column1 datatype,
column2 datatype,
column3 datatype,
....
);
Example-
CREATE TABLE Persons (
PersonID int,
LastName varchar(255),
FirstName varchar(255),
Address varchar(255),
City varchar(255)
); Swapnali Pawar

3.Commands to Handle Tables
Alter , Drop , Insert
Example
ALTER TABLE Customers
ADD Email varchar(255);
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The SQL DROP TABLE Statement
The DROP TABLE statement is used to drop an
existing table in a database.
Syntax
DROP TABLE table_name;
Note: Be careful before dropping a table. Deleting a table will
result in loss of complete information stored in the table!
Example
DROP TABLE myfriends;
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The SQL INSERT INTO Statement
The INSERT INTO statement is used to insert new records in a table.
It is possible to write the INSERT INTO statement in two ways:
1. Specify both the column names and the values to be inserted:
INSERT INTO table_name (column1, column2, column3, ...)
VALUES (value1, value2, value3, ...);
2. If you are adding values for all the columns of the table, you do not need to
specify the column names in the SQL query. However, make sure the order of
the values is in the same order as the columns in the table. Here, the INSERT
INTO syntax would be as follows:
INSERT INTO table_name
VALUES (value1, value2, value3, ...);
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B. Commands for Record Handling
1. Update,Select,Delete
2. With arithmetic,comparision,logical operators
• And
• OR
• Between
• In
• Like
3. Order by
4. Group by
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1. Update,Select,Delete
UPDATE Syntax
The UPDATE statement is used to modify the existing records in a table.
UPDATE table_name
SET column1 = value1, column2 = value2, ...
WHERE condition;
DELETE Syntax
The DELETE statement is used to delete existing records in a table.
DELETE FROM table_name WHERE condition;
Be careful when deleting records in a table! Notice the WHERE clause in the DELETE statement.
The WHERE clause specifies which record(s) should be deleted. If you omit the WHERE clause, all
records in the table will be deleted!
SELECT Syntax
The SELECT statement is used to select data from a database.
The data returned is stored in a result table, called the result-set.
SELECT column1, column2, ...
FROM table_name;
Here, column1, column2, ... are the field names of the table you want to select data
from. If you want to select all the fields available in the table, use the following
syntax:
SELECT * FROM table_name;
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2. With arithmetic,comparision,logical operators
(And,OR,Between,In,Like)
AND Syntax- The AND operator displays a record if all the conditions
separated by AND are TRUE.
FROM table_name
WHERE condition1 AND condition2 AND condition3 ...;
OR Syntax- The OR operator displays a record if any of the conditions separated
by OR is TRUE.
FROM table_name
WHERE condition1 OR condition2 OR condition3 ...;
NOT Syntax- The NOT operator displays a record if the condition(s) is NOT TRUE.
FROM table_name
WHERE NOT condition;
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BETWEEN
The BETWEEN command is used to select values within a given range. The values can be numbers, text,
or dates.
The BETWEEN command is inclusive: begin and end values are included.
The following SQL statement selects all products with a price BETWEEN 10 and 20:
Example
SELECT * FROM Products
WHERE Price BETWEEN 10 AND 20;
SELECT * FROM Products
WHERE Price NOT BETWEEN 10 AND 20;
IN Operator
The IN operator allows you to specify multiple values in a WHERE clause.
The IN operator is a shorthand for multiple OR conditions.
SELECT column_name(s)
FROM table_name
WHERE column_name IN (value1, value2, ...);
Example
SELECT * FROM Customers
WHERE Country IN ('Germany', 'France', 'UK');
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The SQL LIKE Operator
The LIKE operator is used in a WHERE clause to search for a specified pattern in a
column.
There are two wildcards often used in conjunction with the LIKE operator:
• The percent sign (%) represents zero, one, or multiple characters
• The underscore sign (_) represents one, single character
Note: MS Access uses an asterisk (*) instead of the percent sign (%), and a
question mark (?) instead of the underscore (_).
LIKE Syntax
FROM table_name
WHERE columnN LIKE pattern;
SQL LIKE Examples
The following SQL statement selects all customers with a CustomerName starting
with "a":
Example
WHERE CustomerName LIKE 'a%'; Swapnali Pawar

LIKE Operator Description
WHERE CustomerName LIKE 'a%' Finds any values that start with "a"
WHERE CustomerName LIKE '%a' Finds any values that end with "a"
WHERE CustomerName LIKE '%or%' Finds any values that have "or" in any
position
WHERE CustomerName LIKE '_r%' Finds any values that have "r" in the second
position
WHERE CustomerName LIKE 'a_%' Finds any values that start with "a" and are
at least 2 characters in length
WHERE CustomerName LIKE 'a__%' Finds any values that start with "a" and are
at least 3 characters in length
WHERE ContactName LIKE 'a%o' Finds any values that start with "a" and ends
with "o"
Here are some examples showing different LIKE operators with '%' and '_' wildcards:
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3. 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
FROM table_name
ORDER BY column1, column2, ... ASC|DESC;
Example
ORDER BY Country DESC;
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4. The SQL GROUP BY Statement
The GROUP BY statement groups rows that have the same values into
summary rows, like "find the number of customers in each country".
The GROUP BY statement is often used with aggregate functions
(COUNT(), MAX(), MIN(), SUM(), AVG()) to group the result-set by one or
more columns.
GROUP BY Syntax
SELECT column_name(s)
FROM table_name
WHERE condition
GROUP BY column_name(s)
ORDER BY column_name(s);
Example
SELECT COUNT(CustomerID), Country
FROM Customers
GROUP BY Country
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C. SQL Functions
1. Date
2. Numeric
3. Character conversion
4. Group Functions
Avg , Max , Min , Sum , Count
5. Set Operations-
Union , Union all, intersect, minus
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Date Operations :
SELECT CURTIME();
SELECT CURDATE()
SELECT DATE_ADD('1994-16-12',INTERVAL 31 DAY);
SELECT DAYNAME('1994-12-16');
SELECT DAYOFMONTH('1994-12-16');
SELECT DAYOFWEEK('1995-12-16');
SELECT DAYOFYEAR('1995-12-16');
SELECT FROM_DAYS(729669);
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ABS(X)
The ABS() function returns the absolute value of X. Consider the following
example −
SQL> SELECT ABS(2);
2. Numeric Functions
CEILING(X)
These functions return the smallest integer value that is not smaller than X. Consider the
following example −
SQL> SELECT CEILING(3.46);
CEILING(3.46)
4
COS(X)
This function returns the cosine of X. The value of X is given in radians.
SQL>SELECT COS(90);
COS(90)
-0.44807361612917
FLOOR(X)
This function returns the largest integer value that is not greater than X.
SQL>SELECT FLOOR(7.55);
FLOOR(7.55)
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3. Character conversion
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• SELECT CONCAT(first_name, ' ',last_name) as full_name from myfriends;
• SELECT length(first_name) as full_name from myfriends;
• SELECT length(concat(first_name,last_name)) as full_name from myfriends;
• SELECT lower(first_name) as full_name from myfriends;
• SELECT ucase(first_name) as full_name from myfriends;
• SELECT upper(first_name) as full_name from myfriends;
• SELECT ltrim(first_name) as full_name from myfriends;
• SELECT mid(first_name,1,2) as full_name from myfriends;
• SELECT reverse(first_name) as full_name from myfriends;
String Operation
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4. Group Functions
Avg , Max , Min , Sum , Count
COUNT() Syntax-
The COUNT() function returns the number of rows that matches a
specified criterion.
SELECT COUNT(column_name)
FROM table_name
WHERE condition;
AVG() Syntax-
The AVG() function returns the average value of a numeric
column
SELECT AVG(column_name)
FROM table_name
WHERE condition;
SUM() Syntax
The SUM() function returns the total sum of a numeric column.
SELECT SUM(column_name)
FROM table_name
WHERE condition;
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The SQL MIN() and MAX() Function
MIN() Syntax
SELECT MIN(column_name)
FROM table_name
WHERE condition;
MAX() Syntax
SELECT MAX(column_name)
FROM table_name
WHERE condition;
The MAX() function returns the largest value of the selected
column
The MIN() function returns the smallest value of the selected
column.
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5. Set Operations-
Union , Union all, intersect, minus
UNION
The UNION command combines the result set of two or more
SELECT statements (only distinct values). it will eliminate duplicate
rows from its resultset.
The following SQL statement returns the cities (only distinct values)
from both the "Customers" and the "Suppliers" table:
Example
SELECT City FROM Customers
UNION
SELECT City FROM Suppliers
ORDER BY City;
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UNION ALL
The UNION ALL command combines the result set of two
or more SELECT statements (allows duplicate values).
The following SQL statement returns the cities
(duplicate values also) from both the "Customers" and
the "Suppliers" table:
Example
SELECT City FROM Customers
UNION ALL
SELECT City FROM Suppliers
ORDER BY City;
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UNION ALL Example
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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.
SELECT * FROM First
INTERSECT
SELECT * FROM Second;
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Intersect Example
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MINUS
The Minus operation combines results of two SELECT statements
and return only those in the final result, which belongs to the first
set of the result
SELECT * FROM First
MINUS
SELECT * FROM Second;
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MINUS Operation Example
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Student Activity
• Create table myfriends & execute
all queries on that table
CREATE TABLE myfriends
(
last_name VARCHAR(15) NOT NULL,
first_name VARCHAR(15) NOT NULL,
suffix VARCHAR(5) NULL,
sex VARCHAR(1) NULL,
city VARCHAR(20) NOT NULL,
state VARCHAR(2) NOT NULL,
age int
);
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Database Management System 1

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Database Management System 1