manual.texi Use wildcard consistently, not a mix of wild card,

@item MySQL Server

@code{LIKE} is a case-insensitive or case-sensitive operator, depending on

the columns involved. If possible, MySQL uses indexes if the

@code{LIKE} argument doesn't start with a wild-card character.

@code{LIKE} argument doesn't start with a wildcard character.

@item mSQL

Use @code{CLIKE}.

@end table

@item

@cindex wildcards, in @code{mysql.user} table

You can use the wild-card characters @samp{%} and @samp{_} in the @code{Host}

You can use the wildcard characters @samp{%} and @samp{_} in the @code{Host}

field.

@item

@item

@cindex anonymous user

Wild-card characters are not allowed in the @code{User} field, but you can

Wildcard characters are not allowed in the @code{User} field, but you can

specify a blank value, which matches any name.  If the @code{user} table

entry that matches an incoming connection has a blank user name, the user is

considered to be the anonymous user (the user with no name), rather than the

@item @code{'144.155.166.0/255.255.255.0'} @tab @code{'fred'} @tab Same as previous example

@end multitable

Because you can use IP wild-card values in the @code{Host} field (for example,

Because you can use IP wildcard values in the @code{Host} field (for example,

@code{'144.155.166.%'} to match every host on a subnet), there is the

possibility that someone might try to exploit this capability by naming a

host @code{144.155.166.somewhere.com}.  To foil such attempts, MySQL

disallows matching on hostnames that start with digits and a dot. Thus, if

you have a host named something like @code{1.2.foo.com}, its name will never

match the @code{Host} column of the grant tables.  Only an IP number can

match an IP wild-card value.

match an IP wildcard value.

An incoming connection may be matched by more than one entry in the

@code{user} table.  For example, a connection from @code{thomas.loc.gov} by

@itemize @bullet

@item

The wild-card characters @samp{%} and @samp{_} can be used in the @code{Host}

The wildcard characters @samp{%} and @samp{_} can be used in the @code{Host}

and @code{Db} fields of either table.

@item

@itemize @bullet

@item

The wild-card characters @samp{%} and @samp{_}

The wildcard characters @samp{%} and @samp{_}

can be used in the @code{Host} field of either table.

@item

MySQL supports specifying the @code{user_name} value in the form

@code{user@@host}.  If you want to specify a @code{user} string

containing special characters (such as @samp{-}), or a @code{host} string

containing special characters or wild-card characters (such as @samp{%}), you

containing special characters or wildcard characters (such as @samp{%}), you

can quote the user or host name (for example, @code{'test-user'@@'test-hostname'}).

You can specify wildcards in the hostname.  For example,

@code{SHOW} provides information about databases, tables, columns, or

status information about the server. If the @code{LIKE wild} part is

used, the @code{wild} string can be a string that uses the SQL @samp{%}

and @samp{_} wild-card characters.

and @samp{_} wildcard characters.

@menu

* SHOW DATABASE INFO::          Retrieving information about Database, Tables, Columns, and Indexes

Note that in newer MySQL versions, you only see those

database/tables/columns for which you have some privileges.

If the last argument contains a shell or SQL wild-card (@code{*}, @code{?},

If the last argument contains a shell or SQL wildcard (@code{*}, @code{?},

@code{%} or @code{_}) then only what's matched by the wildcard is shown.

This may cause some confusion when you try to display the columns for a

table with a @code{_} as in this case @code{mysqlshow} only shows you

@cindex indexes, and @code{LIKE}

@cindex wildcards, and @code{LIKE}

MySQL also uses indexes for @code{LIKE} comparisons if the argument

to @code{LIKE} is a constant string that doesn't start with a wild-card

to @code{LIKE} is a constant string that doesn't start with a wildcard

character.  For example, the following @code{SELECT} statements use indexes:

@example

mysql> SELECT * FROM tbl_name WHERE key_col LIKE other_col;

@end example

In the first statement, the @code{LIKE} value begins with a wild-card

In the first statement, the @code{LIKE} value begins with a wildcard

character.  In the second statement, the @code{LIKE} value is not a

constant.

MySQL normally uses the index that finds the least number of rows. An

index is used for columns that you compare with the following operators:

@code{=}, @code{>}, @code{>=}, @code{<}, @code{<=}, @code{BETWEEN}, and a

@code{LIKE} with a non-wild-card prefix like @code{'something%'}.

@code{LIKE} with a non-wildcard prefix like @code{'something%'}.

Any index that doesn't span all @code{AND} levels in the @code{WHERE} clause

is not used to optimise the query. In other words:  To be able to use an

@item \%

A @samp{%} character. This is used to search for literal instances of

@samp{%} in contexts where @samp{%} would otherwise be interpreted

as a wild-card character. @xref{String comparison functions}.

as a wildcard character. @xref{String comparison functions}.

@findex _ (wildcard character)

@findex Wildcard character (_)

@item \_

A @samp{_} character. This is used to search for literal instances of

@samp{_} in contexts where @samp{_} would otherwise be interpreted

as a wild-card character. @xref{String comparison functions}.

as a wildcard character. @xref{String comparison functions}.

@end table

Note that if you use @samp{\%} or @samp{\_} in some string contexts, these

@item expr LIKE pat [ESCAPE 'escape-char']

Pattern matching using

SQL simple regular expression comparison. Returns @code{1} (TRUE) or @code{0}

(FALSE).  With @code{LIKE} you can use the following two wild-card characters

(FALSE).  With @code{LIKE} you can use the following two wildcard characters

in the pattern:

@multitable @columnfractions .10 .60

        -> 1

@end example

To test for literal instances of a wild-card character, precede the character

To test for literal instances of a wildcard character, precede the character

with the escape character.  If you don't specify the @code{ESCAPE} character,

@samp{\} is assumed:

@code{DESCRIBE} provides information about a table's columns.  @code{col_name}

may be a column name or a string containing the SQL @samp{%} and @samp{_}

wild-card characters.

wildcard characters.

If the column types are different than you expect them to be based on a

@code{CREATE TABLE} statement, note that MySQL sometimes

Returns a result set consisting of database names on the server that match

the simple regular expression specified by the @code{wild} parameter.

@code{wild} may contain the wild-card characters @samp{%} or @samp{_}, or may

@code{wild} may contain the wildcard characters @samp{%} or @samp{_}, or may

be a @code{NULL} pointer to match all databases.  Calling

@code{mysql_list_dbs()} is similar to executing the query @code{SHOW

databases [LIKE wild]}.

Returns a result set consisting of field names in the given table that match

the simple regular expression specified by the @code{wild} parameter.

@code{wild} may contain the wild-card characters @samp{%} or @samp{_}, or may

@code{wild} may contain the wildcard characters @samp{%} or @samp{_}, or may

be a @code{NULL} pointer to match all fields.  Calling

@code{mysql_list_fields()} is similar to executing the query @code{SHOW

COLUMNS FROM tbl_name [LIKE wild]}.

Returns a result set consisting of table names in the current database that

match the simple regular expression specified by the @code{wild} parameter.

@code{wild} may contain the wild-card characters @samp{%} or @samp{_}, or may

@code{wild} may contain the wildcard characters @samp{%} or @samp{_}, or may

be a @code{NULL} pointer to match all tables.  Calling

@code{mysql_list_tables()} is similar to executing the query @code{SHOW

tables [LIKE wild]}.