Introduction to
Structured Query Language (SQL)
COM S 461 2013-Fall
Instructor: Ying Cai
Iowa State University
1
SQL: What and Why ? (1/2)
Programming Language:
Instructions
Result
Programmers
Computer
2
SQL: What and Why ? (2/2)
Query Language:
Query
Result
DB Users
DBMS
(Database Server)
3
Contents
 Setup a Database Server on your Computer.
 How to define data using SQL:
 Data Definition Language (DDL)
 Create Tables/Update Tables…
 How to manipulate/access data using SQL:
 Data Manipulation Language (DML)
 Insert Data/Update Data/Read Data…
 SQL Functions
4
Setup Database Server (1/2)
 Step 1. Download (Installer/Source code available)
 MySQL
 http://dev.mysql.com/downloads/
 MariaDB
 https://downloads.mariadb.org/
 Step 2. Setup & Configuration
 Port.
 Remote Access.
 Root User.
 Step 3. Connect to server.
 You’ll need: User/PSW, Server IP/Port.
5
Setup Database Server (2/2)
The Clinet/Server Structure
Client 1
DB Connection
Client 2
Database Server
Client 3
6
Programming with SQL
SQL
Data Definition
Language
Data Manipulation
Language
Data Control
Language
1.Create DB/Table
2.Change DB/Table
3.Delete DB/Table
1.Add Data
2.Update Data
3.Remove Data
4. Get Data
Access Control
Authorization
…
7
Data Definition Language
 (Basic) Keywords of DDL:
CREATE
• Create a new Database/Table
ALTER
• Change the definition of an existing DB/table
DROP
• Delete an existing DB/table.
8
Syntax of CREATE
 Create a new database.
CREATE DATABASE db_name;
 Create a new table
Data types:
CREATE TABLE table_name
(
column_1 INT,
column_2 CHAR(10) NOT NULL,
column_3 VARCHAR(256),
column_4 INT DEFAULT 0,
……
);
•
•
•
•
•
INT/INTEGER(size)
DECIMAL(size,d)
CHAR(size)
VARCHAR(size)
Date(yyyymmdd)
9
Syntax of CREATE
 Create a new database.
CREATE DATABASE db_name;
 Create a new table
Data types:
CREATE TABLE table_name
(
column_1 INT,
column_2 CHAR(10) NOT NULL,
column_3 VARCHAR(256),
column_4 INT DEFAULT 0,
……
);
Colunm_1
Colunm_2
•
•
•
•
•
(Empty)
(Empty)
INT/INTEGER(size)
DECIMAL(size,d)
CHAR(size)
VARCHAR(size)
Date(yyyymmdd)
Colunm_3
Colunm_4
(Empty)
(Empty)
10
Syntax of ALTER
 Add a column to an exiting table.
ALTER TABLE table_name
ADD column_name data_type;
 Change a column of an exiting table.
ALTER TABLE table_name
ALTER COLUMN column_name new_data_type;
or
or
CHANGDE COLUMN old_name new_name data_type;
MODIFY COLUMNB column_name new_data_type;
 Delete a column from an exiting table.
ALTER TABLE table_name
DROP COLUMN column_name;
11
Syntax of DROP
 Delete a Database
DROP DATABASE db_name
 Delete a Table.
DROP TABLE table_name
12
Data Manipulation Language
 (Basic) Keywords of DML:
SELECT
• Read data from DB
UPATE
• Change the value of existing
items
INSERT
• Add new items into DB
DELETE
• Remove existing items from
DB
13
Syntax of SELECT
 Use SELET to get desired data in given format:
SELECT column_1 column_2 …
FROM table_1 table_2 …
WHERE condition
ORDER BY expression ASC/DESC
 Example 1: Get students’ Uid and name, who have GPA
higher than 3.5, sorted by their GPA in descending order.
SELECT uid, student_name
FROM students
WHERE gpa > 3.5
ORDER BY gpa DESC
14
Syntax of SELECT
 Example 2: Get all information about female students
who is older than 20.
SELECT *
FROM students
WHERE ( 2013 – YoB ) > 20 AND gener = ‘F’
 Example 3: Get the average speed of all cars in a table
where only moving distance and time are stored.
SELECT (distance/time) AS speed
FROM cars
WHERE time > 0
15
Syntax of SELECT
 Select from Multiple Tables: (Multiple Table Query)
 The DBMS will combine the two tables to generate a new
Virtual Table (Cross Join).
SELECT *
FROM students course
Uid
Name
cid
Name
Students
001
Andy
100
Database
001,002
002
Jack
101
Algorithm
002
16
Syntax of SELECT
 Select from Multiple Tables: (Multiple Table Query)
 The DBMS will combine the two tables to generate a new
Virtual Table (Cross Join).
SELECT *
FROM students course
Uid
Name
cid
Name
Students
001
Andy
100
Database
001,002
001
Andy
101
Algorithm
002
002
Jack
100
Database
001,002
002
Jack
101
Algorithm
002
17
Syntax of SELECT
 Example 4: Show the uid and name of all students who
registered for the Database course.
SELECT student.uid student.name
FROM students course
WHERE course.name = “Database”
AND student.id IN course.students
18
Syntax of SELECT
 Example 5: We have three tables:
Uid
Name
CID
Name
Uid
CID
001
Andy
100
Database
001
100
002
Jack
111
Algorithm
002
111
Student
Course
TA
 Show the name of each course and the name of the TA
assigned to this course.
SELECT course.name, student.name
FROM students course TA
WHERE Courese.Cid = TA.Cid
AND Student.Uid = TA.Uid
19
Syntax of SELECT
 Select Distinct values (No duplicates)
SELECT DISTINCT column_1, column_2 …
FROM table_1, table_2 …
WHERE conditions …
 Example 6: Show students with distinct birthday and
name.
SELECT DISTINCT Name DoB
FROM Student Course
20
Syntax of SELECT
 Select a given number of items
SELECT TOP NUMBER column_1 column_2
FROM table_1 table_2
WHERE conditions…
or
SELECT column_1 column_2
FROM table_1 table_2
WHERE conditions…
LIMIT NUMBER
21
Syntax of SELECT
 Example 7: Show the name of 100 students with the
highest GPA.
SELECT name
FROM students
ORDER BY gpa DESC
LIMIT 100
22
Syntax of Update
 Update the value of existing item(s).
Update table_name
SET
column_1 = value_1
column_2 = value_2
……
WHERE conditions…
23
Syntax of Insert
 Insert new items into a table
INSERT INTO table_name
VALURES
(value_1, value_2 … ), # row 1
(value_1, value_2 … ), # row 2
…. …
24
Syntax of Delete
 Delete items from a table
DELETE FROM table_name
WHERE conditions…
 DELETE without any condition will delete all items in the
table, which is forbidden by many DBMS.
25
SQL Functions
 AVG()
 Calculate the Average of selected data column
SELECT AVG( column_name| expression) AS value_name
FROM table_1, table_2 …
WHERE conditions …
 ORDER BY/LIMIT is no longer necessory.
26
SQL Functions
 COUNT ()
 Count the number of items selected.
SELECT COUNT( column_name| expression) AS value_name
FROM table_1, table_2 …
WHERE conditions …
 MAX () / MIN ()
 Return the Maximal/Minimal value in selected data.
SELECT MAX/MIN( column_name| expression) AS value_name
FROM table_1, table_2 …
WHERE conditions …
27
SQL Functions
 SUM()
 Calculate the sum of selected values.
SELECT SUM( column_name| expression) AS value_name
FROM table_1, table_2 …
WHERE conditions …
28
SQL Leaning resources
 General Introductions and Examples: W3CSchool
 http://www.w3schools.com/sql/
 SQL reference
 MySQL: http://dev.mysql.com/doc/refman/5.6/en/
 T-SQL (Microsoft): http://technet.microsoft.com/enus/library/ms189826(v=sql.90).aspx
 OracleSQL:
http://docs.oracle.com/cd/B19306_01/server.102/b14200
/toc.htm
29
Q&A
30