allbut

rel.allbut([:a, :b, ...])

Problem

Remove some attributes from a relation (this might cause some tuples to become duplicates of others and thus be removed).

Example: What are the different T-shirt variants we stock, if we disregard colors?

Description

Identical to project except that it keeps all attributes except those specified in the argument.

Requirements

The specified attributes must be part of the input relation’s heading.

Examples

Consult the Overview page for the data model used in this example.

suppliers.allbut([:city]).to_a
=>
[{:sid=>"S1", :name=>"Smith", :status=>20},
 {:sid=>"S2", :name=>"Jones", :status=>10},
 {:sid=>"S3", :name=>"Blake", :status=>30},
 {:sid=>"S4", :name=>"Clark", :status=>20},
 {:sid=>"S5", :name=>"Adams", :status=>30}]

Generated SQL

SELECT DISTINCT `t1`.`city`
FROM `suppliers` AS 't1'