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>> Introduction to MySQL

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Introduction

• Structured Query Language (SQL)– Standard Database Language– Manage Data in a DBMS (Database Management

System)• MySQL, Oracle, MS SQL Server

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Databases• Database– Stores data for fast and efficient access– Structured into tables

Name ID Major GPA

Abdur Rahman 312456 CIS 3.97

Ahmed 312198 CS 4.00

Mohammed 312786 CIS 2.78

Rows

Columns

RecordField

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MySQL

• Fast, Reliable, Easy-to-use• Multi-user• Freely available• Network Database of choice (used mostly with

PHP)– Connectivity– Speed– Security

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Getting Started

• Operations on a DBMS (CRUD)– Create– Retrieve– Update– Delete

• Target– Databases– Tables– Records

Note: SQL is not case sensitive

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CREATE

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Create Database

Using a database

CRUDDTR

Create a new DB called MyDBUse that databaseTRY NOW

SYNTAXCREATE DATABASE Database_Name;

USE Database_Name;

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Primary Key

PRIMARY KEY• uniquely identifies each record in a database table• must contain unique values• cannot contain NULL• each table should have a primary key• each table can have only ONE primary key

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Create Table CRUDDTR

SYNTAXCREATE TABLE Table_Name (column_specifications);

For each column• Name of the column• Data type• Size• Other constraints

int (signed, unsigned)double, floatchar, varchartextblobdate, time, datetime

Student_ID Name Major GPA

Create Table students(Student_ID int unsigned,Name varchar(50),Major varchar(3),GPA float,PRIMARY KEY(Student_ID));

TRY NOW

NOT NULLUNIQUECHECKDEFAULT

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Insert Record CRUDDTR

SYNTAXINSERT INTO table_name SET col_name1=value1, col_name2=value2, col_name3=value3, …

OR

Student_ID Name Major GPA

312981 Mohammed

CIS 4.00

TRY NOW

INSERT INTO table_name (col_name1, col_name2) VALUES (value1, value2);

Note: Strings in ‘ ‘(single quotes)

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RETRIEVE

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Retrieve Database

• Listing Existing Databases– show databases;

CRUDDTR

Show databases;TRY NOW

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Retrieve Table• Using a Database– use db-name ;

• Listing Tables in a Database– show tables;

• Table Structure– describe table-name;

CRUDDTR

Look at the table you createdTRY NOW

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Retrieve Record CRUDDTR

SYNTAXSELECT column_name(s)FROM table_name

Using * here will select all columns

TRY NOW

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Retrieve Record CRUDDTR

SELECT

SELECT column_name(s)FROM table_name

DISTINCT (Return only unique values)

WHERE column_name operator value

Operator Description

= Equal

!= Not equal

> Greater than

< Less than

>= Greater than or equal

<= Less than or equal

BETWEEN Between an inclusive range

LIKE Search for a pattern

IN To specify multiple possible values for a column

AND column_name2 operator value2

OR column_name2 operator value2

ORDER BY column_name(s) ASC|DESC

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UPDATE

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Update Database

• Can only rename a Database• Can be done from the DBMS (outside the

SQL)• Other way– Create new database (with new name)– Make dump of old database– Import dumped data into new database– Delete old database

CRUDDTR

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Alter TableCRUDDTR

1. Add a new column “DOB” with type date2. Change the new column’s datatype to year3. Delete Column GPA

TRY NOW

SYNTAXALTER TABLE table_name

ADD column_name datatypeMODIFY column_name datatype

DROP COLUMN column_name

OROR

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Update Record CRUDDTR

SYNTAXUPDATE table_nameSET column1=value1, column2=value2,...WHERE column=value;

RememberChoose a unique (or Primary Key) here else multiple rows will be updatedTRY NOW

Student_ID Name Major DOB

312981 Mohammed

CIS

Add “1990” here

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DELETE

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Delete Record CRUDDTR

SYNTAXDELETE FROM table_nameWHERE column=value;

Delete this record

TRY NOW

Student_ID Name Major DOB

312981 Mohammed

CIS 1990

Note: Remove this to delete all rows.

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Drop TableCRUDDTR

Drop the created tableTRY NOW

SYNTAXDROP TABLE Table_Name;

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Drop DatabaseCRUDDTR

Drop the created databaseTRY NOW

SYNTAXDROP DATABASE Database_Name;