Boolean

[skiflyer]

I know this is a somewhat trivial questoin, but I have actually done my research, and I do have it implemented, I'm just looking for a better way...

(using mySQL 4.0.12)

No pre-defined boolean type in mySQL...

I thought I remembered reading somewhere that I could store booleans in mySQL by flipping a single bit, thereby saving a ton of space... can't seem to see how to do this though... instead I'm using a tiny-int, but if I'm not mistaken in my quick binary math, that's still 8 bits.

Thanks for any help.

-Rob

 

[sleipnir214]

Even if you could flip one bit, you'd have to flip one bit of an existing column type -- and of those, tinyint is the smallest available.

If you had more than one piece of yes/no data to store, you could share a single column. You can perform bitwise logical operations on the tinyint.

You could also declare the column a set. Want the best answers? Ask the best questions:

http://www.catb.org/~esr/faqs/smart-questions.html

TANSTAAFL!

 

[skiflyer]

I meant, I thought BIT was a column type that could be used... in fact I see it on the list in the mySQL docs, but I don't see anything about it or how it's used etc.

-Rob

 

[sleipnir214]

According to the MySQL online documentation, BIT and BOOL are synonyms for TINYINT.

http://www.mysql.com/doc/en/Column_types.html

Want the best answers? Ask the best questions:

http://www.catb.org/~esr/faqs/smart-questions.html

TANSTAAFL!

 

[skiflyer]

Thanks, I'm still getting familar with the docs... must've been a faulty memory of mine.

Thanks for the info.

-Rob

 

[sleipnir214]

I've seen threads on the subject I think you're describing.

But it's just using bitwise-logical operators to turn on and off the bits in a column. Want the best answers? Ask the best questions:

http://www.catb.org/~esr/faqs/smart-questions.html

TANSTAAFL!

 

[skiflyer]

Right, when storing multiple truth values... that makes sense... my table is so simple, but sometimes I just like to play with the big stuff so I can learn it in case I need it later.

good to know, and good to see that line in the docs, I had been staring at the same page and somehow missing the info you clearly pointed out.

Now this weekend I get to learn about implementing foreign keys in mySQL... from the rumors I hear, that should be fun (I'm hoping they're all anti-mySQL zealots who don't know what they're talking about)

-Rob

 

[sleipnir214]

Foreign keys aren't the panacea they're cracked up to be, especially if you control the interface to the data.

Their power really only comes to the fore when you have users able to run arbitrary queries.

If you control access to the data, then your program will not allow the user to enter "9 doors" in a car-describing field which should only take "4 door" or "2 door" (because the related table has only those 2 values).

If your users can run arbitrary queries, then the database server needs to be able to prevent that bad input. Want the best answers? Ask the best questions:

http://www.catb.org/~esr/faqs/smart-questions.html

TANSTAAFL!

 

[skiflyer]

You know, I put forth that same argument in the general database forum, and more than one individual basically called it a ridiculous notion.

Any the way, I don't imagine a scenario where I'll "need" them, but I'm still in my planning stages, and just trying to pick up plenty of knowledge before I start coding the big stuff.

-Rob