Exactly ... Both a=? and c=?1 will use the same parameter. With named parameters you would do something like:
Where a = :a and b = :b and c = :a and d = :d sqlite3_bind_parameter_index(stmt, ":a") -> 1 sqlite3_bind_parameter_index(stmt, ":b") -> 2 sqlite3_bind_parameter_index(stmt, ":d") -> 3 named parameters just create a mapping between unique names -> index so you do not have to track which index number corresponds to which parameter name. If you have lots of parameters and/or a complicated query you can see where this greatly improves maintainability (at a small expense of speed and code size). Many of the traditional types of SQL embeding (for example the EXEC SQL macro in older environments) or the tcl interpreter (for example) will automatically bind named parameters to local variables of the same <name>. Many SQLite wrappers can map parameters the same way, to a dictionary or to object attributes. --- () ascii ribbon campaign against html e-mail /\ www.asciiribbon.org > -----Original Message----- > From: [email protected] [mailto:sqlite-users- > [email protected]] On Behalf Of Igor Korot > Sent: Sunday, 28 April, 2013 14:53 > To: General Discussion of SQLite Database > Subject: Re: [sqlite] Question about binding > > Hi, Keith, > > On Sun, Apr 28, 2013 at 12:34 PM, Keith Medcalf <[email protected]> > wrote: > > > > > http://www.sqlite.org/lang_expr.html#varparam > > > > They are what are called Named Parameters. You use the > > sqlite3_bind_parameter_index to look up the index associated with a name > ... > > > > ?nnn simply means to use index nnn for that parameter. Subsequent bare > ? > > parameter indexes are incremented by 1 from the largest parameter index > > thus far used. > > > > Ie where a= ? and b = ? and c = ?1 and d=? > > > > So it means that: > > [pseudo-code] > sqlite3_bind...( stmt, 1,...); > sqlite3_bind...( stmt, 2,...); > sqlite3_bind...( stmt, 3, ...); > [/pseudo-code] > > and a and c will have 1, b - 2 and c - 3, right? > > Thank you. > > > > Has 3 parameters. A and C use the same bind index and thus the same > > parameter. > > > > --- > > () ascii ribbon campaign against html e-mail > > /\ www.asciiribbon.org > > > > > > > -----Original Message----- > > > From: [email protected] [mailto:sqlite-users- > > > [email protected]] On Behalf Of Igor Korot > > > Sent: Sunday, 28 April, 2013 13:05 > > > To: General Discussion of SQLite Database > > > Subject: [sqlite] Question about binding > > > > > > Hi, ALL, > > > On the page http://www.sqlite.org/c3ref/bind_blob.html it says: > > > > > > [quote] > > > ..... that matches one of following templates: > > > > > > > > > - ? > > > - ?NNN > > > - :VVV > > > - @VVV > > > - $VVV > > > > > > [/quote] > > > > > > > > > What is the purpose of having "NNN" and "VVV"? Are those standard? How > do > > > I > > > use those templates? > > > > > > Everywhere I see an examples which uses just "?" and no other 4 > > templates. > > > > > > > > > Thank you. > > > _______________________________________________ > > > sqlite-users mailing list > > > [email protected] > > > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > > > > > > > > _______________________________________________ > > sqlite-users mailing list > > [email protected] > > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > > > _______________________________________________ > sqlite-users mailing list > [email protected] > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users _______________________________________________ sqlite-users mailing list [email protected] http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
