manual.texi Added note about retrieving ENUM or SET column values

However, values retrieved from the column later have lettercase matching the

values that were used to specify the allowable values at table creation time.

If you retrieve an @code{ENUM} in a numeric context, the column value's index

is returned.  If you store a number into an @code{ENUM}, the number is

treated as an index, and the value stored is the enumeration member with

that index.  (However, this will not work with @code{LOAD DATA}, which treats

all input as strings.)

If you retrieve an @code{ENUM} in a numeric context, the column value's

index is returned.  For example, you can retrieve numeric values from

an @code{ENUM} column like this:

@example

mysql> SELECT enum_col+0 FROM tbl_name;

@end example

If you store a number into an @code{ENUM}, the number is treated as an

index, and the value stored is the enumeration member with that index.

(However, this will not work with @code{LOAD DATA}, which treats all

input as strings.)

@code{ENUM} values are sorted according to the order in which the enumeration

members were listed in the column specification.  (In other words,

@strong{MySQL} stores @code{SET} values numerically, with the low-order bit

of the stored value corresponding to the first set member.  If you retrieve a

@code{SET} value in a numeric context, the value retrieved has bits set

corresponding to the set members that make up the column value.  If a number

is stored into a @code{SET} column, the bits that are set in the binary

representation of the number determine the set members in the column value.

Suppose a column is specified as @code{SET("a","b","c","d")}.  Then the

members have the following bit values:

corresponding to the set members that make up the column value.  For example,

you can retrieve numeric values from a @code{SET} column like this:

@example

mysql> SELECT set_col+0 FROM tbl_name;

@end example

If a number is stored into a @code{SET} column, the bits that

are set in the binary representation of the number determine the

set members in the column value.  Suppose a column is specified as

@code{SET("a","b","c","d")}.  Then the members have the following bit

values:

@multitable @columnfractions .2 .2 .6

@item @code{SET} @strong{member} @tab @strong{Decimal value} @tab @strong{Binary value}