MySQL Basics I

Topics 

• What is MySQL? 
• Installation of MySQL server 
• “mysql” command-line client 
• SQL basics 
  • Concept & terminology 
  • Databases, tables, fields 
  • Insert/Update/Delete 
  • Retrieving records through SELECT 
  • Arithmetic operations 
• Read and execute SQL script file

What is MySQL? 

• Most popular open source database 
  • High performance 
  • High reliability 
  • Ease of use 
• Runs many of the world's most demanding websites 
  • Yahoo, Google, YouTube, ... 
• “M” of LAMP (Linux, Apache, MySQL, PHP) stack 
• Runs on all possible OS platforms

MySQL Products 

• MySQL community server 
  • Free 
• MySQL Enterprise 
  • Commercial 
  • Enterprise features - monitoring 
• MySQL Cluster 
  • Provides fault tolerance 
• MySQL embedded database 
  • Embedded in small devices 
• MySQL Workbench 
  • GUI tool

Installation of MySQL Server

MySQL Server 

• “mysqld” is a runnable program which represents MySQL database server

Installation Options 

• Windows 
  • MySQL database server can be installed either runnable program or Windows service 
• Other platforms (Linux, MacOS, OpenSolaris) 
  • As part of LAMP stack or 
  • Independently as runnable program

Demo: Exercise 1: Installation 1610_mysql_basics1.zip

“mysql” Command-line Client

What is “mysql” command-line client? 

• Comes with MySQL package 
• Connects to the running MySQL database server when run 
• Can be run either in interactive mode or non-interactive mode (batch mode) 
• When run in interactive mode, it provides a shell in which SQL commands can be executed 
• Can be run with many options 
  • mysql --help

Demo: Exercise 2: “mysql” 1610_mysql_basics1.zip

SQL Basics: Concept & Terminology

What is SQL? 

• SQL is language for retrieving and manipulating data in a relational database 
  • Data definition 
  • Data manipulation 
  • Data control 
• Open standard - ANSI 
  • Vendor implementations add vendor-specific features, however

SQL Terminology 

• Table 
  • A set of rows 
  • Analogous to a “file” 
• Row
  • Analogous to a record of a “file” 
• Column 
  • A column is analogous to a field of a record 
  • Each column in a given row has a single value 
• Primary Key 
  • One of more columns whose contents are unique within a table and thus can be used to identify a row of that table

Types of SQL Statements 

• DDL (Data Definition Language) 
  • Used to build and modify the structure of your tables and other objects in the database 
  • Examples: CREATE TABLE, ALTER TABLE, DROP TABLE, CREATE VIEW, ... 
• DML (Data Manipulation Language) 
  • Used to work with the data in tables 
  • INSERT INTO, UPDATE, DELETE 
• DCL (Data Control Language) 
  • Used to control access rights 
  • GRANT, REVOKE

SQL Basics: Databases

Creating a database mysql

mysql> CREATE DATABASE mydb;
Query OK, 1 row affected (0.01 sec)

Setting a default database

mysql> USE mydb;

Database changed

Dropping Databases

mysql> DROP DATABASE temp_db;
Query OK, 0 rows affected (0.01 sec)
mysql> DROP DATABASE IF EXISTS temp_db;
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> SHOW DATABASES;
+--------------------+
|Database |
+--------------------+
|information_schema |
| mydb |
| mysql |
| test |
+--------------------+
4 rows in set (0.00 sec)

SQL Basics: Tables

Creating a Table

mysql> CREATE TABLE person (
 -> person_id SMALLINT UNSIGNED NOT NULL,
 -> first_name VARCHAR(45) NOT NULL,
 -> last_name VARCHAR(45) NOT NULL,
 -> PRIMARY KEY (person_id)
 -> ) ENGINE=InnoDB;
Query OK, 0 rows affected (0.14 sec)
mysql> SHOW TABLES;
+----------------+
| Tables_in_mydb |
+----------------+
| person |
+----------------+
1 row in set (0.00 sec)

Altering table name (Two options)

mysql> ALTER TABLE person rename to person1;
Query OK, 0 rows affected (0.06 sec)
mysql> SHOW TABLES;
+----------------------+
| Tables_in_mydb |
+----------------------+
| person1 |
+----------------------+
1 row in set (0.00 sec)
mysql> RENAME TABLE person1 TO whatever;
Query OK, 0 rows affected (0.05 sec)
mysql> SHOW TABLES;
+----------------------+
| Tables_in_mydb |
+----------------------+
| whatever |
+----------------------+
1 row in set (0.00 sec)

Altering field name and type

mysql> ALTER TABLE person CHANGE last_name surname varchar(30);
Query OK, 0 rows affected (0.62 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> DESCRIBE person;
+------------+----------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+------------+----------------------+------+-----+---------+----------------+
| person_id | smallint(5) unsigned | NO | PRI | NULL |
| first_name | varchar(45) | NO | | NULL | |
| surname | varchar(30) | YES | | NULL | |
+------------+----------------------+------+-----+---------+----------------+
3 rows in set (0.01 sec)

Adding or removing fields

mysql> ALTER TABLE person ADD age smallint(3) unsigned not null;
Query OK, 0 rows affected (0.42 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> DESCRIBE person;
+------------+----------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+------------+----------------------+------+-----+---------+----------------+
| person_id | smallint(5) unsigned | NO | PRI | NULL |
| first_name | varchar(45) | NO | | NULL | |
| surname | varchar(30) | YES | | NULL | |
| age | smallint(3) unsigned | NO | | NULL | |
+------------+----------------------+------+-----+---------+----------------+
4 rows in set (0.01 sec)
mysql> ALTER TABLE person DROP first_name;
Query OK, 0 rows affected (0.25 sec)
Records: 0 Duplicates: 0 Warnings: 0

Dropping Tables

mysql> SHOW TABLES;
+-------------------+
| Tables_in_temp_db |
+-------------------+
| temp_table |
+-------------------+
1 row in set (0.00 sec)
mysql> DROP TABLE temp_table;
Query OK, 0 rows affected (0.06 sec)
mysql> DROP TABLE IF EXISTS temp_table;
Query OK, 0 rows affected, 1 warning (0.12 sec)
mysql> SHOW TABLES;
Empty set (0.00 sec)

Working with tables from Multiple Databases

mysql> SELECT * FROM temp_db.temp_table;
+---------+---------------------+
| temp_id | temp_whatever |
+---------+---------------------+
| 1 | life is good |
| 2 | life is even better |
+---------+---------------------+
2 rows in set (0.00 sec)
mysql> SELECT * FROM mydb.student;
+------------+------------+-----------+-----+-------+
| student_id | first_name | last_name | age | grade |
+------------+------------+-----------+-----+-------+
| 1 | yuna | kim | 19 | 4 |
| 2 | kelly | jones | 22 | 5 |
+------------+------------+-----------+-----+-------+
2 rows in set (0.00 sec)

SQL Basics: Fields

• Field Definitions 
  • Each field has 
  • Field name 
  • Data type 
  • Field modifier or constraint

Field Data types - Integers 

• TINYINT 
  • 1 byte, -128 to 127 (signed), 0 to 255 (unsigned) 
• SMALLINT 
  • 2 bytes, -32768 to 32767 (signed), 0 to 65535 (unsigned) 
• MEDIUMINT 
  • 3 bytes 
• INT 
  • 4 bytes 
• BIGINT 
  • 8 bytes

Field Data types 

• FLOAT 
  • single precision floating-point value 
• DOUBLE 
  • double precision floating-point value 
• DECIMAL 
  • decimal values 
• BIT 
  • bit value 
  • b'0101'

Field Data Types 

• CHAR 
  • Fixed length strings up to 255 characters 
• VARCHAR 
  • Variable length strings up to 255 characters 
• DATE, TIME, YEAR 
• DATETIME, TIMESTAMP 
• ENUM, SET 
  • Predefined set of values

Field Modifiers

• NULL or NOT NULL 
  • Indicates if the field can be null or not 
• DEFAULT 
  • Assigns default value if no value is specified when a new record is inserted 
• AUTO_INCREMENT 
  • MySQL automatically generates a number (by incrementing the previous value by 1) 
  • Used for creating primary key 
• CHARACTER SET 
  • Specifies the character set for string values

Demo: Exercise 3: Databases, Tables, Fields 1610_mysql_basics1.zip

SQL Basics: INSERT/UPDATE/DELETE

INSERT'ing a single record

mysql> INSERT INTO person (person_id, first_name, last_name, age)
 -> VALUES (1, 'sang', 'shin', 88);
Query OK, 1 row affected (0.10 sec)
mysql> SELECT * FROM person;
+-----------+------------+-----------+-----+
| person_id | first_name | last_name | age |
+-----------+------------+-----------+-----+
| 1 | sang | shin | 88 |
+-----------+------------+-----------+-----+
1 row in set (0.00 sec)

INSERT'ing multiple records

mysql> INSERT INTO person (person_id, first_name, last_name, age)
 -> VALUES
 -> (2, 'kelly', 'jones', 22),
 -> (3, 'jack', 'kennedy', 56),
 -> (4, 'paul', 'kennedy', 34),
 -> (5, 'daniel', 'song', 24),
 -> (6, 'nichole', 'scott', 9);
Query OK, 3 rows affected (0.05 sec)
Records: 3 Duplicates: 0 Warnings: 0

Deleting recored(s)

mysql> DELETE FROM person WHERE age < 10;
Query OK, 1 row affected (0.07 sec)

Updating record(s)

mysql> UPDATE person SET age = 88
 -> WHERE age = 99 OR first_name = 'paul';
Query OK, 1 row affected, 2 warnings (0.04 sec)
Rows matched: 1 Changed: 1 Warnings: 2
mysql> SELECT * FROM person;
+-----------+------------+-----------+-----+
| person_id | first_name | last_name | age |
+-----------+------------+-----------+-----+
| 1 | sang | shin | 88 |
| 2 | kelly | jones | 22 |
| 3 | jack | kennedy | 56 |
| 4 | paul | kennedy | 88 |
+-----------+------------+-----------+-----+
4 rows in set (0.00 sec)

Demo: Exercise 4: INSERT/UPDATE/DELETE 1610_mysql_basics1.zip

SQL Basics: SELECT

Retrieving some fields selectively

mysql> SELECT last_name, age FROM person;
+-----------+-----+
| last_name | age |
+-----------+-----+
| shin | 88 |
| jones | 22 |
| kennedy | 56 |
| kennedy | 34 |
| song | 24 |
+-----------+-----+
5 rows in set (0.00 sec)

Retrieving with WHERE clause

mysql> SELECT first_name, age FROM person
 -> WHERE age > 50;
+------------+-----+
| first_name | age |
+------------+-----+
| sang | 88 |
| jack | 56 |
+------------+-----+
2 rows in set (0.00 sec)
mysql> SELECT first_name, last_name, age FROM person
 -> WHERE age < 50 AND first_name LIKE '%niel';
+------------+-----------+-----+
| first_name | last_name | age |
+------------+-----------+-----+
| daniel | song | 24 |
+------------+-----------+-----+
1 row in set (0.00 sec)

Retrieving records in order

mysql> SELECT last_name, age FROM person
 -> ORDER BY age ASC;
+-----------+-----+
| last_name | age |
+-----------+-----+
| jones | 22 |
| song | 24 |
| kennedy | 34 |
| kennedy | 56 |
| shin | 88 |
+-----------+-----+
5 rows in set (0.00 sec)
mysql> SELECT * FROM person
 -> ORDER BY age DESC;
+-----------+------------+-----------+-----+
| person_id | first_name | last_name | age |
+-----------+------------+-----------+-----+
| 1 | sang | shin | 88 |
| 3 | jack | kennedy | 56 |
| 4 | paul | kennedy | 34 |
| 5 | daniel | song | 24 |
| 2 | kelly | jones | 22 |
+-----------+------------+-----------+-----+
5 rows in set (0.00 sec)

Retrieving limited number of records

mysql> SELECT * from person
 -> ORDER BY age DESC
 -> LIMIT 3;
+-----------+------------+-----------+-----+
| person_id | first_name | last_name | age |
+-----------+------------+-----------+-----+
| 1 | sang | shin | 88 |
| 3 | jack | kennedy | 56 |
| 4 | paul | kennedy | 34 |
+-----------+------------+-----------+-----+
3 rows in set (0.00 sec)

Demo: Exercise 5: SELECT 1610_mysql_basics1.zip

Basic SQL Commands: Arithmetic Functions

Arithmetic operations

mysql> SELECT 3 + 6;
+-------+
| 3 + 6 |
+-------+
| 9 |
+-------+
1 row in set (0.00 sec)
mysql> SELECT 45 * (1+2);
+------------+
| 45 * (1+2) |
+------------+
| 135 |
+------------+
1 row in set (0.00 sec)

COUNT, AVG, SUM

mysql> SELECT COUNT(age) FROM person;
+------------+
| COUNT(age) |
+------------+
| 5 |
+------------+
1 row in set (0.04 sec)
mysql> SELECT AVG(age) from person;
+----------+
| AVG(age) |
+----------+
| 44.8000 |
+----------+
1 row in set (0.00 sec)
mysql> SELECT SUM(age) FROM person;
+----------+
| SUM(age) |
+----------+
| 224 |
+----------+
1 row in set (0.00 sec)

MIN, MAX

mysql> SELECT MIN(age) FROM person;
+----------+
| MIN(age) |
+----------+
| 22 |
+----------+
1 row in set (0.00 sec)
mysql> SELECT MAX(age) FROM person;
+----------+
| MAX(age) |
+----------+
| 88 |
+----------+
1 row in set (0.00 sec)

Demo: Exercise 6: Arithmetic Functions 1610_mysql_basics1.zip

Reading and Executing SQL Script File

mysql> SOURCE c:/tmp/student.sql
Query OK, 0 rows affected (0.10 sec)

Demo: Exercise 7: SQL File 1610_mysql_basics1.zip

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