Update document on sqlite3_mprintf() and related functions. Discuss the

%w format and point out that obscure ANSI-C formats are not supported.
No changes to code.

FossilOrigin-Name: f8917ba4d917bc762b3b252466ab72a8a70dc0d8

src/sqlite.h.in

@@ -2232,6 +2232,10 @@ void sqlite3_free_table(char **result);
 **
 ** These routines are work-alikes of the "printf()" family of functions
 ** from the standard C library.
+** These routines understand most of the common K&R formatting options,
+** plus some additional non-standard formats, detailed below.
+** Note that some of the more obscure formatting options from recent
+** C-library standards are omitted from this implementation.
 **
 ** ^The sqlite3_mprintf() and sqlite3_vmprintf() routines write their
 ** results into memory obtained from [sqlite3_malloc()].
@@ -2264,7 +2268,7 @@ void sqlite3_free_table(char **result);
 ** These routines all implement some additional formatting
 ** options that are useful for constructing SQL statements.
 ** All of the usual printf() formatting options apply.  In addition, there
-** is are "%q", "%Q", and "%z" options.
+** is are "%q", "%Q", "%w" and "%z" options.
 **
 ** ^(The %q option works like %s in that it substitutes a nul-terminated
 ** string from the argument list.  But %q also doubles every '\'' character.
@@ -2317,6 +2321,12 @@ void sqlite3_free_table(char **result);
 ** The code above will render a correct SQL statement in the zSQL
 ** variable even if the zText variable is a NULL pointer.
 **
+** ^(The "%w" formatting option is like "%q" except that it expects to
+** be contained within double-quotes instead of single quotes, and it
+** escapes the double-quote character instead of the single-quote
+** character.)^  The "%w" formatting option is intended for safely inserting
+** table and column names into a constructed SQL statement.
+**
 ** ^(The "%z" formatting option works like "%s" but with the
 ** addition that after the string has been read and copied into
 ** the result, [sqlite3_free()] is called on the input string.)^