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My SQL

Part 2 - Basic SQL - Page 3

Before you can use the MySql database, you will need to know how to enter commands using the MS dos prompt.

MS DOS

On my computer the MS dos program is located at:

C:\Windows\command.com

So I suggest you create a shortcut to the command.com program. When you run the program, you will see the following prompt:

C:\WINDOWS>

Which means that it is addressing the 'Windows' directory.

CHANGE DIRECTORY

Since MySql is located at C:\mysql\bin you will need to change to that directory. So type at the command prompt:

C:\WINDOWS> cd c:\mysql\bin

The prompt will change as follows:

C:\mysql\bin>

RUNNING MYSQL

Type at the prompt:

C:\mysql\bin> mysql

And you will see:

Welcome to the MySQL monitor. Commands end with ; or \g.

Your MySQL connection id is 3 to server version: 4.0.18

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql>

To return to the MS dos prompt, type 'quit'.

SHOW DATABASES

Type at the prompt:

mysql> show databases;

And you will see the databases, which already exist:

Databases

mysql
test

2 rows in set (0.17 sec)

If you forget to type ';' at the end of a statement, you will see the following prompt:

-->

To return to the 'mysql' prompt, type ';'

For example:

-> ;

mysql>

STRUCTURED QUERY LANGUAGE

The first SQL command was 'show databases;'. Now it is time to use some more:

mysql> use mysql;

Database changed

mysql>

The syntax is "use database-name;" which means the name of the database. The name of this database, just to confuse you, is 'mysql'. So in other words, you are using a database called 'mysql'.

SHOW TABLES

Before you can show the tables in a database, the database has to be selected first. Otherwise, you will see:

ERROR 1046: No Database selected

So starting from the beginning:

mysql> use mysql;

Database changed

mysql> show tables;

You will see a list of the tables in the 'mysql' database.

Tables_in_mysql

columns_priv
db
func
host
tables_priv
user

6 rows in set (0.06 sec)

EXPLAIN TABLE NAME

One of the tables is called 'user'. So type at the prompt:

mysql> explain user;

And the screen will fill up with a load of useless information.

The syntax is "explain table-name;", the table-name is 'user', so you type "explain user;"

You can, of course, explain any of the tables, and "explain db;" will produce a better example.

CREATE DATABASE

The syntax is "create database database-name;", the database-name is 'idiots', so you type "create database idiots;"

mysql> create database idiots;

Query ok, 1 row affected (0.05 sec)

If the database already exists, you will see:

ERROR 1007: Can't create database 'idiots'. Database exists

mysql>

SHOW DATABASES

Type at the prompt:

mysql> show databases;

And you will see the database 'idiots', added to the list:

Databases

idiots
mysql
test

3 rows in set (0.05 sec)

Continued