Learning Mysql

PRIMARY KEY (`artist_id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 |
+--------+------------------------------------------------+
1 row inset sec)
We’ve reformatted the output slightly to fit better in this book. You’ll notice that the output includes content added by MySQL that wasn’t in our original CREATE TABLE
statement:
• The names of the table and columns are enclosed in backticks. This isn’t necessary,
but it does avoid any parsing problems that can occur through using reserved words and special characters, as discussed previously An additional default
ENGINE
clause is included, which explicitly states the table
type that should be used. The setting in a default installation of MySQL is
MyI
SAM
, so it has no effect in this example An additional DEFAULT CHARSET=latin1
clause is included, which tells MySQL what character set is used by the columns in the table. Again, this has no effect in a default, Latin-character-set-based installation
Column Types
This section describes the column types you can use in MySQL. It explains when each should be used and any limitations it has. We’ve ordered the choices in two sections:
first, the commonly used, and, second, the less frequently used choices. Skip the second part if you want to and revisit it when one of the common choices doesn’t fit your needs;
it’s certainly worth reviewing when you’re tackling the exercises at the end of this chapter.
Common column types
The following are the six commonly used column types in MySQL tables:
INT[(width)] UNSIGNED [ZEROFILL]
The most commonly used numeric type. Stores integer (whole number) values in the range –2,147,483,648 to 2,147,483,647. If the optional
UNSIGNED
keyword is added, the range is 0 to 4,294,967,295. The keyword
INT
is short for INTEGER, and they can be used interchangeably. An
INT
column requires four bytes of storage space.
You can also include optional
width
and
ZEROFILL
arguments to left-pad the values with zeros up to the specified length. The maximum
width
is 255. The
width
pa- rameter has no effect on what is stored. If you store a value wider than the
width
,
the
width
value is ignored. Consider this example:
mysql> CREATE TABLE numbers (my_number INT) ZEROFILL );
Query OK, 0 rows affected (0.01 sec)
mysql> INSERT INTO numbers VALUES(3),(33),(333),(3333),(33333),(333333);

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