I'm trying to run the Sequel example from http://sequel.rubyforge.org/. Everything works fine on sqlite, but fails when I switch to postgres.
This is the connection code:
DB = Sequel.connect(:adapter=>'postgres', :host=>'localhost', :database=>'testing', :user=>'postgres', :default_schema=>'sequel')
This is the error I get:
postgres.rb:145:in `async_exec': PG::Error: ERROR: relation "items" does not exist (Sequel::DatabaseError)
LINE 1: INSERT INTO "items" ("price", "name") VALUES (12.45377636338...
I'm suspecting that the issue is Sequel trying to execute INSERT INTO "items" instead "sequel.items", even though :default_schema is correctly set.
Anyone have any idea what i'm doing wrong?
Thanks in advance.
Edit - this is the code used:
require "rubygems"
require "sequel"
# connect to an in-memory database
#DB = Sequel.sqlite
DB = Sequel.connect(:adapter=>'postgres', :host=>'localhost', :database=>'testing', :user=>'postgres', :default_schema=>'sequel')
# create an items table
DB.create_table :items do
primary_key :id
String :name
Float :price
end
# create a dataset from the items table
items = DB[:items]
# populate the table
items.insert(:name => 'abc', :price => rand * 100)
items.insert(:name => 'def', :price => rand * 100)
items.insert(:name => 'ghi', :price => rand * 100)
# print out the number of records
puts "Item count: #{items.count}"
Looks like you're missing the password in the connect method (that's the only difference from the documentation example). Its common for the password to just be the username, so try that if you're not sure what the password is.
It's also suggested to use a different postgresql user with each project, which also makes naming the user intuitive (the project name.) That avoids potentially clashing names.
Anyway, see if this works:
DB = Sequel.postgres 'testing', host: 'localhost', default_schema: 'sequel',
user: 'postgres', password: 'postgres'
Related
I need to create a view with an order by-clause with sequel, tinytds and MSSQL
When I do so, I get the error
TinyTds::Error: The ORDER BY clause is invalid in views, inline functions, derived tables, subqueries, and common table expressions, unless TOP or FOR XML is also specified. (Sequel::DatabaseError)
My examplecode:
require 'sequel'
DB = Sequel.tinytds(
:host => 'server',
:database=> 'DB',
)
#Remove data from previous test
DB.drop_table(:testtab1) if DB.table_exists?(:testtab1)
DB.drop_view(:v_testtab1) rescue Sequel::DatabaseError
DB.drop_view(:v_testtab2) rescue Sequel::DatabaseError
DB.create_table(:testtab1){
primary_key :id
field :a, :type => :nvarchar, :size => 10
field :b, :type => :nvarchar, :size => 10
}
#Here the error comes up
#"SELECT * FROM `testtab1` ORDER BY `b`"
DB.create_view(:v_testtab1, DB[:testtab1].order_by(:b))
See solution on SQL-side is easy. Instead of the
SELECT * FROM `testtab1` ORDER BY `b`
I need a
SELECT top 100 percent * FROM `testtab1` ORDER BY `b`
I found a solution with an additional obsolete column (without the column dummy I get an invalid comma):
sel = DB[:testtab1].select(Sequel.lit('top 100 percent "" as dummy'), *DB[:testtab1].columns)
#SELECT top 100 percent "" as dummy, [ID], [A], [B] FROM [TESTTAB1]
DB.create_view(:v_testtab2, sel.order_by(:b))
A similar solution can be made with limit:
#Take a big number to get all entries.
#DB[:testtab1].count would take the number in moment of view creation, not usage.
sel = DB[:testtab1].limit(99999999999)
#SELECT TOP (99999999999) * FROM [TESTTAB1]
DB.create_view(:v_testtab3, sel.order_by(:b))
But I'm looking for a nicer solution. Is there another better possibility?
If it is important:
Ruby 2.1
Sequel 4.19
tiny_tds-0.6.2-x64-mingw32
MSSQL 10.50.2500.0, 64 bit
I am using Sequel with prostgres and Sinatra. I want to do an autocomplete search. I’ve verified my jQuery which sends a GET works fine.
The Ruby code is:
get '/search' do
search = params[:search]
DB[:candidates].select(:last).where('last LIKE ?', '_a_').each do |row|
l = row[:last]
end
end
The problem is the Sequel query:
I have tried every possible configuration of the query that I can think of with no luck.
So, for example, in the above query I get all the people who have "a" in their last name but when I change the query to:
DB[:candidates].select(:last).where('last LIKE ?', 'search')
or
DB[:candidates].select(:last).where('last LIKE ?', search) # (without '')
I get nothing.
I have done warn params.inspect which indicates the param search is being passed, so I am stuck.
Any ideas how the query should be written?
Finally, the second part of the question the results (when it works with '_a_') are rendered as {:last=>"Yao"} I would like just Yao, how can I do that?
I have tried numerous different types of query including raw SQL but no luck. Or is the approach just plain wrong?
Just installed Sequel and made working example:
require "rubygems"
require "sequel"
# connect to an in-memory database
DB = Sequel.sqlite
# create an items table
DB.create_table :items do
primary_key :id
String :name
Float :price
end
# create a dataset from the items table
items = DB[:items]
# populate the table
items.insert(:name => 'abc', :price => rand * 100)
items.insert(:name => 'def', :price => rand * 100)
items.insert(:name => 'ghi', :price => rand * 100)
items.insert(:name => 'gui', :price => rand * 100)
# print out the number of records
puts "Item count: #{items.count}"
# print out the average price
puts "The average price is: #{items.avg(:price)}"
recs = items.select(:name).where(Sequel.like(:name, 'g%'))
recs.each do |rec|
puts rec.values
end
I think you will get the point.
UPDATED
So in your case you should try this:
DB[:candidates]
.select(:last)
.where(Sequel.like(:last, "#{search}%"))
.map{|rec| rec.values}.flatten
It should return array of found strings.
Copy/pasting from the Sequel documentation:
You can search SQL strings in a case sensitive manner using the Sequel.like method:
items.where(Sequel.like(:name, 'Acme%')).sql
#=> "SELECT * FROM items WHERE (name LIKE 'Acme%')"
You can search SQL strings in a case insensitive manner using the Sequel.ilike method:
items.where(Sequel.ilike(:name, 'Acme%')).sql
#=> "SELECT * FROM items WHERE (name ILIKE 'Acme%')"
You can specify a Regexp as a like argument, but this will probably only work on PostgreSQL and MySQL:
items.where(Sequel.like(:name, /Acme.*/)).sql
#=> "SELECT * FROM items WHERE (name ~ 'Acme.*')"
Like can also take more than one argument:
items.where(Sequel.like(:name, 'Acme%', /Beta.*/)).sql
#=> "SELECT * FROM items WHERE ((name LIKE 'Acme%') OR (name ~ 'Beta.*'))"
Open up a Sequel console (not your Sinatra app) and play with the query until you get results back. Since you say you want only the last column your query should be something like:
# Search anywhere inside the last name
DB[:candidates].where( Sequel.ilike(:last, "%#{search}%") ).select_map(:last)
# Find last names starting with the search string
DB[:candidates].where( Sequel.ilike(:last, "#{search}%") ).select_map(:last)
Uglier alternatives:
DB[:candidates]
.select(:last)
.where( Sequel.ilike(:last, "%#{search}%") )
.all
.map{ |hash| hash[:last] }
DB[:candidates]
.select(:last)
.where( Sequel.ilike(:last, "%#{search}%") )
.map( :last )
If you want to rank the search results by the best matches, you might be interested in my free LiqrrdMetal library. Instead of searching on the DB, you would pull a full list of all last names into Ruby and use LiqrrdMetal to search through them. This would allow a search string of "pho" to match both "Phong" as well as "Phrogz", with the former scoring higher in the rankings.
I am trying to figure out how to parameterize an SQL string before handing it off to be executed, but sadly I find a lot of this on the internet:
sql = "SELECT * FROM table_name WHERE thing LIKE '%#{input}%'"
Which is a bad thing...however, parameterizing sql queries is available in the underlying Sequel library, which is what TinyTDS is built on top of. So I know it's possible. I am just having a hard time figuring it out.
I really wish it could be as simple as this:
#client = TinyTds::Client.new(
:adapter => 'sqlserver',
:host => host,
:database => db,
:username => username,
:password => password)
sql = "SELECT * FROM table_name WHERE thing LIKE ?"
safe_sql = #client.prepare(sql, input)
result = #client.execute(safe_sql)
I seem to have found something called a Dataset class in the sourcecode, which has a prepare method. The question is, how do I use it? Do I need to create another object before handing it off to the execute() method in the #client object? I couldn't find an initialize or a new method, so simple instantiation seems like the wrong way to go.
I implemented the Sequel gem with TinyTds as the adapter. This allows you to parameterize SQL queries. See example below:
require "tiny_tds"
require 'sequel'
DB = Sequel.connect(
adapter: 'tinytds',
host: "dataserver",
database: "database",
user: "username",
password: "password"
)
I then was able to make a SQL insert statement with my values parametrized.
posts_table = DB[:posts]
posts_table.insert(:author => 'John Smith', :title => 'How to parametrize sql queries')
I'm connecting to a MS SQL database.
I've got a single table inheritance structure in my application whereby Admins and Mods extends a User class. The table uses a discriminator value so each record has a type of either "admin" or "mod"
When it comes to finding a user (on login) I'd like to write the following:
current_user = User.find(params[:email => email])
However, this creates SQL which includes
SELECT ...... WHERE ("type" IN ('User') AND .....
This means that the record cannot be found. However if I type
current_user = Admin.find(params[:email => email])
I get the user (if they are an admin).
I've also tried the following to no avail since the 'type' IN ('User') is still created:
current_user = User.first(:email => email, :type => [Admin, Mod])
Thanks in advance for any help on this
I think it should be
current_user = User.first(:email => email, :type => ['Admin', 'Mod'])
What is the best way to run simple SQL scripts in a database (preferably DBM implementation agnostically)?
So, for illustration purposes, using your best/suggested way, I'd like to see a script that creates a few tables with names from an array ['cars_table', 'ice_cream_t'], deletes all elements with id=5 in a table, and does a join between two tables and prints the result formatted in some nice way.
I've heard of Python and PL/SQL to do this
Ruby/Datamapper seems very attractive
Java + JDBC, maybe
Others?
Some of these are mostly used in a full application or within a framework. I'd like to see them used simply in scripts.
Ruby/Sequel is currently my weapon of choice.
Short example from the site:
require "rubygems"
require "sequel"
# connect to an in-memory database
DB = Sequel.sqlite
# create an items table
DB.create_table :items do
primary_key :id
String :name
Float :price
end
# create a dataset from the items table
items = DB[:items]
# populate the table
items.insert(:name => 'abc', :price => rand * 100)
items.insert(:name => 'def', :price => rand * 100)
items.insert(:name => 'ghi', :price => rand * 100)
# print out the number of records
puts "Item count: #{items.count}"
# print out the average price
puts "The average price is: #{items.avg(:price)}"
By using SQL DDL (Data Definition Language), which can be done db agnostically, if you're careful.
There are examples at the Wikipedia article:
http://en.wikipedia.org/wiki/Data_Definition_Language