The sample given above is how these questions should be answered.

 

A construction company works with a database that stores information about contractors, materials, and sites. The Consignment relation records instances of a contractor delivering materials for a construction site. The schema for the database used in this question is as follows: (note that primary keys are shown underlined, foreign keys in bold). Provide Relational Algebra (NOT SQL) queries, with description as necessary to find the following information. Each question is worth 2 marks. NOTE: You can use the symbols , II, etc or the words 'PROJECT', 'RESTRICT' etc as you prefer. You do not need to try to make efficient queries-just correct ones. Where you use a join, always show the join condition. Provide a description to explain how the query will run. It is recommended to use symbols. Make sure about the superscripts and subscripts Make sure to add steps and description. If no descriptions or steps provided even if query is correct you will receive zero marks. Each Query is 2 marks. What I will look for: Correct use of operators Inclusion of correct Relations (i.e., if an attribute is listed that is not from the listed relations, then the query is incorrect) Specification of join conditions; this is explicitly listed above. No join leads to half marks Similarly, if joins are specified between more than two relations at once (e.g., a*b*c is incorrect, and may be more appropriately written as a (b c) or similar half marks will be deducted 1. Show the quantity of Materials delivered on site-ID "Site04". Steps: Query: Description: Note: Query is simple. Make sure about the condition and operators. Also, whether it is single quoted or double quoted. 2. Show the weight of the Wood type material named "Beautiful Grey Door". Steps: Query: Description: Note: Query is simple. Make sure about the condition and operators. Also, whether it is single quoted or double quoted.