The Sequel gem qualified query column name with table double underscores

Question

Using the Sequel gem:

employees = DB[:prm_master__employee.identifier]
.join(:prm_master__employee_custom_fields.identifier, :employee => :employee)
.where("termination_date >= ?","06/01/2012")
.or("termination_date = NULL")
.and("employee = 'holderl'")

The above fails with:

~/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/sequel-3.41.0/lib/sequel/adapters/tinytds.rb:221:in `fields': TinyTds::Error: Ambiguous column name 'employee'. (Sequel::DatabaseError)

I understand the error (same column names between joined tables, e.g employee), but do not know how I can qualify the employee condition in the and statement since the table uses the identifier method to ignore the underscores.

FYI: You're using three backticks as an attempt to mark a block of code. That doesn't work right. Use four spaces to indent instead. See the [Advanced Markdown documentation](http://stackoverflow.com/editing-help) for more information. — the Tin Man, Dec 03 '12 at 16:20
Github markdown is far superior. the four space indent is impossible. — lukemh, Feb 10 '14 at 03:17

score 14 · Accepted Answer · edited Jun 05 '19 at 07:35

14

The answer is to actually qualify the column name using:

Sequel.qualify(:table, :column)

Or the equivalent shorter syntax:

Sequel[:table][:column]

resulting in:

employees = DB[:prm_master__employee.identifier]
.join(:prm_master__employee_custom_fields.identifier, :employee => :employee)
.where("termination_date >= ?","06/01/2012")
.or("termination_date = NULL")
.and(Sequel.qualify(:prm_master__employee_custom_fields.identifier, :employee)  => "holderl")

edited Jun 05 '19 at 07:35

Gabriel Hautclocq

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answered Dec 03 '12 at 08:52

lukemh

5,043
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1

This can also be used on model relationships to avoid ambiguity in `JOIN`s. – Arman H Jun 19 '16 at 06:47
There's also the shorter syntax `Sequel[:table][:column]` (added it to the answer) – Gabriel Hautclocq Jun 05 '19 at 07:33

score 0 · Answer 2 · answered Dec 03 '12 at 08:23

0

User alias. OR put table_name.column_name

answered Dec 03 '12 at 08:23

vijikumar

1,805
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yes i understand that, but how to do that in sequel gem when double underscore cannot be used? see my answer. – lukemh Dec 03 '12 at 08:53

The Sequel gem qualified query column name with table double underscores

2 Answers2