ruby - Sequel gem increment -

i trying use ruby sequel gem db operations.

i stuck incrementing , decrementing values.

the doc says should work, though seems strange me able add number , symbol.

2.0.0-p247 :019 > require 'sequel'  => true  2.0.0-p247 :020 > s = sequel.connect('sqlite://db.sqlite')  => #<sequel::sqlite::database: "sqlite://db.sqlite">  2.0.0-p247 :021 > s[:query_volume].update_sql(:queries =>  3)  => "update `query_volume` set `queries` = 3"  2.0.0-p247 :022 > s[:query_volume].update_sql(:queries => :queries + 3) nomethoderror: undefined method `+' :queries:symbol     (irb):21     /users/avandra/.rvm/rubies/ruby-2.0.0-p247/bin/irb:16:in `<main>' 

but can see gives undefined method on queries symbol. kindof concurs why strange me.

i tried using curly braces, gives error:

2.0.0-p247 :023 > s[:query_volume].update_sql{:queries => :queries + 3} syntaxerror: (irb):23: syntax error, unexpected =>, expecting '}' s[:query_volume].update_sql{:queries => :queries + 3}                                        ^         /users/avandra/.rvm/rubies/ruby-2.0.0-p247/bin/irb:16:in `<main>' 

and using

2.0.0-p247 :033 >   s[:query_volume].update_sql{queries = queries + 3}  => "update `query_volume` set "  

just gives badly formatted sql...

could shed light on how can done?

you should use sequel.expr that:

s[:query_volume].update_sql(:queries => sequel.expr(3) + :queries)