Selecting MySQL Column Types

MySQL stores data in your table in columns. Each column usually contains only a specific class of information. A database that has a table that contains contact information might have the following columns: Name, Address, City, State, Zip, Phone, FAX,Client_Number

Each column has a column type and most column types require that you specify a size. For instance, varchar(60) would probably be a good column type and size for the Name column, since it is hard to imagine someone having a name longer than 60 characters. varchar is a somewhat generic column type that can store most of the characters that appear on your keyboard.

Column Name	Maximum Size	Notes
varchar	255 characters	Can store most of the characters that appear on your keyboard. When in doubt, use this column type.
char	255 characters	Should be used only to store characters that tend to have the same width. For instance, varchar(2) would be a good choice for a field that will only contain US state abbreviations, since no state abbreviation is longer than 2 characters. You could also use varchar in this example (and MySQL may convert it to varchar anyway), but selecting char won't necessarily hurt. For columns containing longer and variable length content, don't use char, or MySQL will make your database consume more disk space than is necessary.
int	a whole number less than 2,140,000,000 (2.14 billion)	Should be used to store whole numbers only. A whole number is a number like 8876543 that contains no decimal parts or spaces. Phone numbers like (740) 975-8891 and prices like $4.24 can't be stored in int columns because they are not whole numbers.
text	65,000 characters	Can store up to 65KB of text consisting of most keyboard characters. Note: your browser may not be able to send 65KB of text via an HTML form.
mediumtext	mediumtext up to 16,000,000 characters	Can store up to 16MB of keyboard character type text. Note: there is no browser that will package and send 16MB via an HTML form, so mediumtext might be overkill for the great majority of applications.
float	floating point numbers	Consists of two parts, a whole number and a decimal number. It takes the form float(w,d) where w is the max number of digits that the whole number can contain and d is the max number of digits that the decimal can contain. For example, the largest number that float(4,2) can hold is 9999.99