Which MySQL data type to use for storing boolean values
Since MySQL doesn't seem to have any 'boolean' data type, which data type do you 'abuse' for storing true/false information in MySQL?
Especially in the context of writing and reading from/to a PHP script.
Over time I have used and seen several approaches:
- tinyint, varchar fields containing the values 0/1,
- varchar fields containing the strings '0'/'1' or 'true'/'false'
- and finally enum Fields containing the two options 'true'/'false'.
None of the above seems optimal. I tend to prefer the tinyint 0/1 variant, since automatic type conversion in PHP gives me boolean values rather simply.
So which data type do you use? Is there a type designed for boolean values which I have overlooked? Do you see any advantages/disadvantages by using one type or another?
Answer
For MySQL 5.0.3 and higher, you can use BIT. The manual says:
As of MySQL 5.0.3, the BIT data type is used to store bit-field values. A type of BIT(M) enables storage of M-bit values. M can range from 1 to 64.
Otherwise, according to the MySQL manual you can use BOOL or BOOLEAN, which are at the moment aliases of tinyint(1):
Bool, Boolean: These types are synonyms for TINYINT(1). A value of zero is considered false. Non-zero values are considered true.
MySQL also states that:
We intend to implement full boolean type handling, in accordance with standard SQL, in a future MySQL release.
References: http://dev.mysql.com/doc/refman/5.5/en/numeric-type-overview.html