A Guide to MySQL 3

2 Introduction  Structured Query Language (SQL): Popular and widely used language for retrieving and manipulating database data Developed in mid-1970s under the name SEQUEL Renamed SQL in 1980 Used by most DBMSs

A Guide to MySQL 3 Starting MySQL  Windows XP Click Start button Point to All Programs Point to MySQL on menu Point to MySQL Server 4.1 Click MySQL Command Line Client  Must enter password in Command Line Client window

A Guide to MySQL 4 Obtaining Help in MySQL  Type \h at MySQL> prompt  Type “help” followed by name of command help contents help union

A Guide to MySQL 5

6

7 Creating a Database  Must create a database before creating tables  Use CREATE DATABASE command  Include database name

A Guide to MySQL 8 Changing the Default Database  Default database: database to which all subsequent commands pertain  USE command, followed by database name: Changes the default database Execute at the start of every session

A Guide to MySQL 9 Creating a Table  Describe the layout of each table in the database  Use CREATE TABLE command  TABLE is followed by the table name  Follow this with the names and data types of the columns in the table  Data types define type and size of data

A Guide to MySQL 10 Table and Column Name Restrictions  Names cannot exceed 18 characters  Must start with a letter  Can contain letters, numbers, and underscores (_)  Cannot contain spaces

A Guide to MySQL 11 Creating the REP Table

A Guide to MySQL 12 Entering Commands in MySQL  Commands are free-format; no rules stating specific words in specific positions  Press ENTER to move to the next line in a command  Indicate the end of a command by typing a semicolon  Commands are not case sensitive

A Guide to MySQL 13 Running SQL Commands

A Guide to MySQL 14 Editing SQL Commands  Statement history: stores most recently used command  Editing commands: Use arrow keys to move up, down, left, and right Use Ctrl+A to move to beginning of line Use Ctrl+E to move to end of line Use Backspace and Delete keys

A Guide to MySQL 15 Errors in SQL Commands

A Guide to MySQL 16 Editing MySQL Commands  Press Up arrow key to go to top line  Press Enter key to move to next line if line is correct  Use Right and Left arrow keys to move to location of error  Press ENTER key when line is correct  If Enter is not pressed on a line, line not part of the revised command

A Guide to MySQL 17 Dropping a Table  Can correct errors by dropping (deleting) a table and starting over  Useful when table is created before errors are discovered  Command is followed by the table to be dropped and a semicolon  Any data in table also deleted

A Guide to MySQL 18 Data Types  For each table column, type of data must be defined  Common data types: CHAR(n) VARCHAR(n) DATE DECIMAL(p,q) INT SMALLINT

A Guide to MySQL 19 Nulls  A special value to represent situation when actual value is not known for a column  Can specify whether to allow nulls in the individual columns  Should not allow nulls for primary key columns

A Guide to MySQL 20 Implementation of Nulls  Use NOT NULL clause in CREATE TABLE command to exclude the use of nulls in a column  Default is to allow null values  If a column is defined as NOT NULL, system will reject any attempt to store a null value there

A Guide to MySQL 21 Adding Rows to a Table  INSERT command : INSERT INTO followed by table name VALUES command followed by specific values in parentheses Values for character columns in single quotation marks

A Guide to MySQL 22 The Insert Command To add new rows modify previous INSERT command Use same editing techniques as those used to correct errors

A Guide to MySQL 23 Adding Additional Rows

A Guide to MySQL 24 The INSERT Command with Nulls  Use a special format of INSERT command to enter a null value in a table  Identify the names of the columns that accept non-null values, then list only the non-null values after the VALUES command  Enter only non-null values  Precisely indicate values you are entering by listing the columns

A Guide to MySQL 25 The INSERT Command with Nulls (continued)

A Guide to MySQL 26 Viewing Table Data  Use SELECT command to display all the rows and columns in a table  SELECT * FROM followed by the name of the table  Ends with a semicolon

A Guide to MySQL 27 Viewing Table Data (continued)

A Guide to MySQL 28 Correcting Errors In the Database  UPDATE command is used to update a value in a table  DELETE command allows you to delete a record  INSERT command allows you to add a record

A Guide to MySQL 29 Correcting Errors in the Database (continued)

A Guide to MySQL 30 Correcting Errors in the Database (continued)

A Guide to MySQL 31 Saving SQL Commands  Allows you to use commands again without retyping  Different methods for each SQL implementation you are using Oracle SQL*Plus and SQL*Plus Worksheet use a script file Access saves queries as objects MySQL uses an editor to save text files

A Guide to MySQL 32 Saving SQL Commands  Script file: File containing SQL commands Use a text editor or word processor to create Save with a.txt file name extension Run in MySQL:  SOURCE file name  \. file name Include full path if file is in folder other than default

A Guide to MySQL 33 Creating the Remaining Database Tables  Execute appropriate CREATE TABLE and INSERT commands  Save these commands to a secondary storage device

A Guide to MySQL 34 Describing a Table