Just to settle a boolean data type question.

Houdini

In a forum elsewhere there was a question concerning the use of radio buttons and the stated that they were placing values into data fields that were TINY INT(1) which I believe is also a BOOLEAN data type and will accept only the values of 0 or 1, am I correct in my thinking since I pointed out that they were in fact using a BOOLEAN whether they knew it or not?

sneakyimp

http://en.wikipedia.org/wiki/Boolean
http://mirriamwebster.com/dictionary/boolean

and from here:
http://dev.mysql.com/doc/refman/4.1/en/numeric-type-overview.html

BIT
In versions of MySQL up to and lincluding 4.1, BIT is a synonym for TINYINT(1).

TINYINT[(M)] [UNSIGNED] [ZEROFILL]
A very small integer. The signed range is -128 to 127. The unsigned range is 0 to 255.

BOOL, BOOLEAN
These types are synonyms for TINYINT(1). The BOOLEAN synonym was added in MySQL 4.1.0. A value of zero is considered false. Non-zero values are considered true.

Houdini

BOOL, BOOLEAN

These types are synonyms for TINYINT(1). The BOOLEAN synonym was added in MySQL 4.1.0. A value of zero is considered false. Non-zero values are considered true.

This is kind of close, one reason I asked is becuase when a set up a BOOLEAN and you look at the structure it ends being
aName TINYINT(1),
in the structure, so I would be safe in saying that a TINY INT with a size of 1 is in fact a BOOLEAN data type, correct?

sneakyimp

well, wikipedia says

A boolean value is a truth value, either "true" or "false", often coded 1 and 0, respectively.

that's pretty much the way i think of it too. if you can't put anything but 1 or 0 in a tinyint(1) then I would say that, for all intents and purposes, they are the same damn thing.

i can't tell if the dictionary def is more concise or vague:

Bool·ean
Pronunciation: 'bü-lE-&n
Function: adjective
Etymology: George Boole died 1864 English mathematician
: of, relating to, or being a logical combinatorial system (as Boolean algebra) that represents symbolically relationships (as those implied by the logical operators AND, OR, and NOT) between entities (as sets, propositions, or on-off computer circuit elements) <Boolean expression> <Boolean search strategy for information retrieval>

Sxooter

You slightly misunderstand what the precision setting on an integer does in MySQL...

If you declare something to be tinyint(1), you can still put something over 1 character in length into it.

To quote the MySQL manual:

11.2. Numeric Types:

Another extension is supported by MySQL for optionally specifying the display width of an integer value in parentheses following the base keyword for the type (for example, INT(4)). This optional display width specification is used to left-pad the display of values having a width less than the width specified for the column.

So, that (1) doesn't do what you think it does. If you need constraints, you're using the wrong database...

sneakyimp

aha! i did say "if you can't put anything...". i wasn't sure really. that's probably gonna bit me in the ass someday.

Sxooter

Oh no, not insulting ya there. I thought the same exact thing the first time I saw them. It seemed the obvious thing to do. Just that it was one of those things that made me go huh??? at first.

sneakyimp

i'm not insulted. i'm still a little confused by what the (1) really does. it's really just specifying how many characters you can store in a tinyint? so it could be any number 0-9?

Sxooter

No, it doesn't stop you from putting things into a tinyint, it affects padding when you pull it out.

So, a (1) doesn't do anything really.