Added docs for escaping placeholders using a backslash and get_info(9000).

Author: timbunce

Changes

@@ -16,6 +16,8 @@ DBI::Changes - List of significant changes to the DBI
     Fixed compilation error on bleadperl due GVSV no longer being an lvalue
         [Dagfinn Ilmari Manns�ker]
 
+    Added docs for escaping placeholders using a backslash.
+    Added docs for get_info(9000) indicating ability to escape placeholders.
     Added multi_ prefix for DBD::Multi (Dan Wright) and ad2_ prefix for
         DBD::AnyData2
 

DBI.pm

@@ -2420,6 +2420,11 @@ If the C<:>I<N> form of placeholder is supported by the driver you're using,
 then you should be able to use either L</bind_param> or L</execute> to bind
 values. Check your driver documentation.
 
+Some drivers allow you to prevent the recognition of a placeholder by placing a
+single backslash character (C<\>) immediately before it. The driver will remove
+the backslash character and ignore the placeholder, passing it unchanged to the
+backend. If the driver supports this then L</get_info>(9000) will return true.
+
 With most drivers, placeholders can't be used for any element of a
 statement that would prevent the database server from validating the
 statement and creating a query execution plan for it. For example:
@@ -4969,6 +4974,13 @@ of information types to ensure the DBI itself works properly:
    41  SQL_CATALOG_NAME_SEPARATOR  '.'           '@'
   114  SQL_CATALOG_LOCATION        1             2
 
+Values from 9000 to 9999 for get_info are officially reserved for use by Perl DBI.
+Values in that range which have been assigned a meaning are defined here:
+
+C<9000>: true if a backslash character (C<\>) before placeholder-like text
+(e.g. C<?>, C<:foo>) will prevent it being treated as a placeholder by the driver.
+The backslash will be removed before the text is passed to the backend.
+
 =head3 C<table_info>
 
   $sth = $dbh->table_info( $catalog, $schema, $table, $type );