MySQL can be an intimidating program. All of the commands have to be
entered through a command prompt; there is no visual interface. Because
of this, having basic knowledge of how to create and manipulate a
database can save you a lot of time and headaches. Follow this guide to
create a database of US states and their populations
Creating and Manipulating a Database
-
- Create the database. From the MySQL command line, enter the command
CREATE DATABASE <DATABASENAME>;
. Replace<DATABASENAME>
with the name of your database. It cannot include spaces.
CREATE DATABASE us_states;
Note: Commands do not have to be entered in upper-case.
Note: All MySQL commands must end with ";". If you forgot to include the semicolon, you can enter just ";" on the next line to process the previous command.
- Create the database. From the MySQL command line, enter the command
-
- Display a list of your available databases. Enter the command
SHOW DATABASES;
to list all of the databases you have stored. Besides the databse you just created, you will also see amysql
database and atest
database. You can ignore these for now.
- Display a list of your available databases. Enter the command
-
- Select your database. Once the database has been created, you will need to select it in order to begin editing it. Enter the command
USE us_states;
. You will see the messageDatabase changed
, letting you know that your active database is nowus_states
.
- Select your database. Once the database has been created, you will need to select it in order to begin editing it. Enter the command
-
- Create a table. A table is what houses your
database’s information. To create one, you will need to enter all of
your table formatting in the initial command. To create a table, enter
the following command:
CREATE TABLE states (id INT NOT NULL PRIMARY KEY AUTO_INCREMENT, state CHAR(25), population INT(9));
. This will create a table named "states" with three fields:id
,state
, andpopulation
.
- The
INT
command will make theid
field contain only numbers (integers). - The
NOT NULL
command makes sure that theid
field cannot be left blank. - The
PRIMARY KEY
designates theid
field as the key field in the table. The key field should be set to a field that cannot contain any duplicates. - The
AUTO_INCREMENT
command will automatically assign increasing values into theid
field, essentially automatically numbering each entry. - The
CHAR
(characters) andINT
(integers) commands designate the types of data allowed in those fields. The number next to the commands indicated how many characters or integers can fit in the field.
- Create a table. A table is what houses your
database’s information. To create one, you will need to enter all of
your table formatting in the initial command. To create a table, enter
the following command:
-
- Create an entry in the table. Now that the table has
been created, it’s time to start entering your information. Use the
following command to input your first entry:
INSERT INTO states (id, state, population) VALUES (NULL, ‘Alabama’, ‘4822023’);
- This is essentially telling the database to enter the information provided into the three corresponding fields in the table.
- Since the
id
field contains the commandNOT NULL
, enteringNULL
as the value will force it to automatically increment to 1, thanks to theAUTO_INCREMENT
command.
- Create an entry in the table. Now that the table has
been created, it’s time to start entering your information. Use the
following command to input your first entry:
- Create more entries. You can create multiple entries using a single command. To enter the next three states, use the following command:
INSERT INTO states (id, state, population) VALUES (NULL, ‘Alaska’, ‘731449’), (NULL, ‘Arizona’, ‘6553255’), (NULL, ‘Arkansas’, ‘2949131’);
. This will create a table that looks like the following:
- Create more entries. You can create multiple entries using a single command. To enter the next three states, use the following command:
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