Some options are “boolean” and control behavior
that can be turned on or off. For example, the
mysql client supports a
--column-names option that
determines whether or not to display a row of column names at
the beginning of query results. By default, this option is
enabled. However, you may want to disable it in some instances,
such as when sending the output of mysql into
another program that expects to see only data and not an initial
To disable column names, you can specify the option using any of these forms:
--disable-column-names --skip-column-names --column-names=0
prefixes and the
=0 suffix all have the same
effect: They turn the option off.
The “enabled” form of the option may be specified in any of these ways:
--column-names --enable-column-names --column-names=1
As of MySQL 5.5.10, the values
FALSE are also recognized for boolean options
(not case sensitive).
If an option is prefixed by
--loose, a program
does not exit with an error if it does not recognize the option,
but instead issues only a warning:
mysql --loose-no-such-optionmysql: WARNING: unknown option '--no-such-option'
--loose prefix can be useful when you run
programs from multiple installations of MySQL on the same
machine and list options in an option file, An option that may
not be recognized by all versions of a program can be given
--loose prefix (or
loose in an option file). Versions of the
program that recognize the option process it normally, and
versions that do not recognize it issue a warning and ignore it.
mysqld enables a limit to be placed on how
large client programs can set dynamic system variables. To do
this, use a
--maximum prefix with the variable
name. For example,
--maximum-query_cache_size=4M prevents any
client from making the query cache size larger than 4MB.