Flags in a database rows, best practices

Question

I am asking this out of a curiosity. Basically my question is when you have a database which needs a row entry to have things which act like flags, what is the best practice

Answer 1

If the flags have very different meanings and are used directly in SQL queries or VIEWS, then using multiple columns of type BOOLEAN might be a good idea.

Put each flag into an extra column, because you'll read and modify them separately anyway. If you want to group the flags, just give their column names a common prefix, i.e. instead of:

CREATE TABLE ... (
    warnings INTEGER,
    errors   INTEGER,
    ...
)

you should use:

CREATE TABLE ... (
    warning_foo BOOLEAN,
    warning_bar BOOLEAN,
    warning_...
    error_foo   BOOLEAN,
    error_bar   BOOLEAN,
    error_...   BOOLEAN,
    ...
)

Although MySQL doesn't have a BOOLEAN type, you can use the quasi standard TINYINT(1) for that purpose, and set it only to 0 or 1.