8/25/2023 0 Comments Mysql boolean fieldThe reason I have articles written on the above two issues is because I've personally run into these two issues and wasted hours trying to understand the issue and come up with a work-around. As such, if you are performing a LEFT OUTER JOIN on a BIT field and attempt to provide a default value with COALESCE(), you have to CAST() the resultant value back to an UNSIGNED type in order to use the value as a Truthy within your application code. The MySQL driver for Java returns binary data when BIT is used in a COALESCE() call. As such, in order to translate a BIT(1) result into a true / false data-type, you have add special type-casing logic to your database client configuration. After all, a BIT column represents binary data, which is what the Buffer represents in Node.js. The MySQL driver for Node.js returns BIT data as a Buffer because, of course it would. But, there are downsides to using a binary field in order to represent a true-false value: Since there's no semantically meaningful difference between the two data-types when it comes to representing Boolean values, neither data-type is "more correct". We can only treat them as Boolean values when our developers agree to treat them as Boolean values.īoth BIT(1) and TINYINT require a byte of storage. Neither BIT nor TINYINT is a "Boolean" value. So, from a physical stand-point, you're not "saving space" by using a BIT instead of a TINYINT when attempting to represent a Boolean value. Which is also the amount of storage required by a TINYINT. Meaning, in order to store a single bit, you have to store 8-bits. Now, storage-wise, there's also no difference between a BIT(1) and a TINYINT because a BIT field is actually stored in bytes. So, semantically speaking, neither BIT nor TINYINT are "Booleans" but, they can both be overloaded to represent a Boolean value if, and only if, the developers working on that application all agree on said social contract. And, like the BIT field, the only reason that it can represent a true-false value within an application is because the developers working on that application have all agreed to treat it as such. The only reason that it can represent a true-false value within an application is because the developers working on that application have all agreed to treat it as such.Ī TINYINT field is also not a true-false data type - it's a numeric data type. A BIT field contains "bits": N-number of bits, between 1 and 64. Because, at least in MySQL, a BIT field isn't a true-false data type - it's a binary data type. Semantically speaking, a BIT field is no more clear or meaningful than a TINYINT field when it comes to storing Boolean data. Instead, I use a TINYINT column.ĬAUTION: There is no "right" answer on this topic - this is just my opinion based on my experience and the choices that have come back to haunt me / make my database interactions more challenging. Since the theme of my week appears to be database interactions (having looked at index structure query-performance on "membership" tables and prepared statements in the JDBC driver), I figured I would end the week on more database-related "hot take": I no longer use BIT columns to store "Boolean" data in MySQL.
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