MySQL 中的 True/False 与 0/1

Question

Which is faster in a MySQL database? Booleans, or using zero and one to represent boolean values? My frontend just has a yes/no radio button.

Answer 1

Some "front ends", with the "Use Booleans" option enabled, will treat all TINYINT(1) columns as Boolean, and vice versa.

This allows you to, in the application, use TRUE and FALSE rather than 1 and 0.

This doesn't affect the database at all, since it's implemented in the application.

There is not really a BOOLEAN type in MySQL. BOOLEAN is just a synonym for TINYINT(1), and TRUE and FALSE are synonyms for 1 and 0.

If the conversion is done in the compiler, there will be no difference in performance in the application. Otherwise, the difference still won't be noticeable.

You should use whichever method allows you to code more efficiently, though not using the feature may reduce dependency on that particular "front end" vendor.

Answer 2

In MySQL TRUE and FALSE are synonyms for TINYINT(1) .

So therefore its basically the same thing, but MySQL is converting to 0/1 - so just use a TINYINT if that's easier for you

PS
The performance is likely to be so minuscule (if at all), that if you need to ask on StackOverflow, then it won't affect your database :)

Answer 3

Bit is also an option if tinyint isn't to your liking. A few links:

• Which MySQL data type to use for storing boolean values
• What is the difference between BIT and TINYINT in MySQL?

Not surprisingly, more info about numeric types is available in the manual .

One more link: http://blog.mclaughlinsoftware.com/2010/02/26/mysql-boolean-data-type/

And a quote from the comment section of the article above:

• TINYINT(1) isn't a synonym for bit(1).
• TINYINT(1) can store -9 to 9.
• TINYINT(1) UNSIGNED: 0-9
• BIT(1): 0, 1. (Bit, literally).

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Edit: This edit (and answer) is only remotely related to the original question...

Additional quotes by Justin Rovang and the author maclochlainn (comment section of the linked article).

Excuse me, seems I've fallen victim to substr-ism: TINYINT(1): -128-+127 TINYINT(1) UNSIGNED: 0-255 (Justin Rovang 25 Aug 11 at 4:32 pm)

True enough, but the post was about what PHPMyAdmin listed as a Boolean, and there it only uses 0 or 1 from the entire wide range of 256 possibilities. (maclochlainn 25 Aug 11 at 11:35 pm)

Answer 4

If you are into performance, then it is worth using ENUM type. It will probably be faster on big tables, due to the better index performance.

The way of using it (source: http://dev.mysql.com/doc/refman/5.5/en/enum.html ):

CREATE TABLE shirts (
    name VARCHAR(40),
    size ENUM('x-small', 'small', 'medium', 'large', 'x-large')
);

But, I always say that explaining the query like this:

EXPLAIN SELECT * FROM shirts WHERE size='medium';

will tell you lots of information about your query and help on building a better table structure. For this end, it is usefull to let phpmyadmin Propose a table table structure - but this is more a long time optimisation possibility, when the table is already filled with lots of data.