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Database Answers Combo 1997-2000 |
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PART A Multiple Choice Items
Attempt all questions in this part. Each question is worth 1 mark. Each question has only one correct response. For each question select the response that is correct. Signify your answer by circling the label (a, b, c or d) of the correct response. If you change your answer, completely erase your original answer. Questions where two or more responses are selected will score no marks.
1997 PART A Multiple Choice Items
11. Which of the following is not a benefit of distributed information processing systems?
(a) Failure of a hardware component has less impact.
(b) Remote sites are able to operate in their own time zones.
(c) Local access to data improves response time.
(d) Data integrity is improved.12. In database terminology, what is a relation?
(a) A link between two tables
(b) A table
(c) A foreign key
(d) An index13. Consider the following statements about relational databases:
You can have relations without relationships.
You can have relationships without relations.
With reference to these statements, select the best of the following alternatives.
(a) Both statements are true.
(b) The first is true but the second is false.
(c) The first is false but the second is true.
(d) Both statements are false.END OF 1997 PART A
1998 PART A Multiple Choice Items
11. Which statement about database models is correct?
(a) Links between tables in relational databases are held by data values in keys (namely, foreign key and primary key values).
(b) Hierarchical databases store data in sets (and run on mainframe computers).
(c) Network databases make use of inexpensive personal computers linked to the Internet.
(d) In a flat file database, the DBMS manages the links between tables.12. Which statement about a relation in second normal form (2NF) is correct?
(a) The relation has a primary key that may contain a null value.
(b) The relation contains repeating groups.
(c) All attributes that are not part of the key depend on all attributes in the key.
(d) The relation has no unique key. (There is no non-key attribute that depends on another non-key attribute.)13. Which statement about a data dictionary is correct?
(a) A data dictionary holds definitions of data, that is, data about data.
(b) A data dictionary holds common data that will be shared between computer systems.
(c) The online version of the Australian Macquarie Dictionary is an example of a data dictionary.
(d) A data dictionary allows computer systems to translate code from one programming language to another.END OF 1998 PART A
1999 PART A Multiple Choice Items12. The major reason relational databases are made up of normalised tables is to:
(a) Reduce the memory required.
(b) Decrease the response time.
(c) Reduce the storage of redundant data.
(d) Decrease the number of tables required.13. Which statement is correct? Relations in Third Normal Form must have:
(a) All non-key attributes dependent only on the key.
(b) A key consisting of more than one attribute.
(c) A key consisting of just one attribute.
(d) No attributes which are not part of the key.END OF 1999 PART A
2000 PART A Multiple Choice Items13. Which statement about a relation in first normal form is correct?
(a) All non-key attributes are dependent on the whole of the primary key.
(b) The relation has a primary key that may contain a null value.
(c) Data items may not be repeated for a specific attribute.
(d) The relation may not contain repeating groups of data for a specific key.14. Given the descriptions shown below of the tables ORDER and SALESPERSON, which of the following attributes is a foreign key?
ORDER
ORDER_NUMBER
ORDER_DATE
SALESPERSON_NUMBER
AMOUNTSALESPERSON
SALESPERSON_NUMBER
SALESPERSON_NAME
SALESPERSON_COMMISSION(a) SALESPERSON_NUMBER
(b) ORDER_NUMBER
(c) AMOUNT
(d) SALESPERSON_NAME15. Your company wants to send an advertising leaflet to all Kalroojalup residents with at least 2 hectares of property. To select the appropriate records from the database, which selection rules should you use?
(a) Suburb EQUALS Kalroojalup OR Area GREATER THAN 2
(b) Suburb EQUALS Kalroojalup AND Area GREATER THAN 2
(c) Suburb EQUALS Kalroojalup OR Area GREATER THAN OR EQUAL TO 2
(d) Suburb EQUALS Kalroojalup AND Area GREATER THAN OR EQUAL TO 2.END OF 2000 PART A
1997 PART B Short AnswersQuestion 20. (3 marks)
In a relational database system:(a) What is a relationship? (2 lines)A relationship is a link between two tables.
(b) What is a tuple? (2 lines)
A tuple is a row in a table
(c) What is an attribute? (2 lines)
An attribute is a column in a table
(d) What is a primary key? (2 lines)
A primary key is one or more attributes which together uniquely identify a tuple
(e) What is a foreign key? (2 lines)
A foreign key is one or more attributes in a table which are also the primary key of another table. Links between tables are held by the same data value in a foreign key attribute and its corresponding primary key attribute in another table.
(f) What is an index? (2 lines)
An index is an extra file or storage area holding the association between the indexed attribute and the record number of the original data. (An index is used to speed up processing.)
END OF 1997 PART B
1998 PART B Short Answers
17. In a distributed database application, you may choose to duplicate data at more than one location. Give one advantage and one disadvantage of doing this. [2 marks]
One advantage is faster access to data.One disadvantage is that updating is more complex—you have to update the original and the duplicate.
END OF 1998 PART B
1999 PART B Short Answers
25. A student can belong to many sports clubs. A sports club has many student members.
An entity-relationship model of this situation consists of two entities Student and Sports Club with a many to many relationship between them. However, most relational database systems do not directly support many to many relationships, but do support one to many relationships. Explain, using a diagram or otherwise, how you would change the model to use the commonly supported one to many relationship. (2 marks)
Change a many to many relationship to two relationships of one to many with an intersection entity added (between them). The primary key of the intersection entity may consist (at least, in part) of the keys of its two parents. Certainly the key of the parents should be present as foreign keys on the intersection entity.
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END OF 1999 PART B
2000 PART B Short Answers
21. The secretary of a yacht club wants to keep track in the yacht club database of all boat owners and their boats. Given the two entities BOAT and OWNER draw an entity-relationship diagram showing the attributes they might have and their relationship. (1/3 page) (2 marks)
0.5 mark for each entity (with suitable attributes)
1 mark for the relationship
END OF 2000 PART B
1997 PART C Extended Answers
Question 26. (23 marks)
A relational database system has been set up to assist with the management of this year's Tertiary Entrance Examinations (TEE). The following are tables used in this database. Primary keys are underlined.STUDENT (student-ID, student-name, date-of-birth, school-name, aggregate-score)
SCHOOL (school-name, address, phone, principal)
TEE SUBJECT (subject-ID, subject-name, exam-date)
STUDENT SUBJECT (student-ID, subject-ID, exam-mark, school-mark)
- A student's aggregate-score is derived from the school-mark and exam-mark in all subjects.
- Some data is already recorded in the tables and is shown below.
- Some records have column values set to 'null'. The 'null' value is not the same as zero or a blank. It means that data is unavailable or unknown. The TEE database does not permit a primary or foreign key to have a value of 'null'. Other fields except for student-name may have a value of 'null'.
- Each student enrolled has a student-ID number that is used for all his or her subjects.
STUDENT student-ID student-name date-of-birth school-name aggregate-score 1003 JOHN MURPHY 12/04/1980 WA HIGH null 1452 MARY KANTOR 17/03/1980 ST JUDES null
SCHOOL school-name address phone principal WA HIGH 23 Collins Terrace, Perth 08 9236 7890 George Lisson ST JUDES 145 Main St, Castleton 08 9371 5644 June Cotton
TEE SUBJECT subject-ID subject-name exam-date INFOSYS Information Systems 12/11/1997 ECON Economics 15/11/1997 GEOG Geography 23/11/1997
STUDENT SUBJECT student-ID subject-ID exam-mark school-mark 1003 GEOG null 56 1003 ECON null 78 1452 GEOG null 80 1452 ECON null 68 (a) Draw a diagram in the frame provided to represent the database design. Show all tables and their attributes (primary and foreign keys and non-key attributes) and underline the primary keys. Mark the foreign keys with the code 'fk'. (half a page available) (5 marks)
(b) Complete the following grid giving details of the primary and foreign keys in the remaining three database relations (tables). Note that the first row has been completed for you. (3 marks)
Table Primary Key First Foreign Key Link is to Table Second Foreign Key Link is to Table STUDENT student-ID school-name SCHOOL SCHOOL school-name TEE SUBJECT subject-ID STUDENT SUBJECT student-ID and
subject-IDstudent-ID STUDENT subject-ID TEE SUBJECT (c) This grid shows details about the relationships between the tables. Complete the grid by placing an X in each row. Note that the first row has been completed for you. (1 mark)
TABLE 1 TABLE 2 1 : 1 many : many 1 : many many : 1 SCHOOL STUDENT X STUDENT STUDENT SUBJECT X TEE SUBJECT STUDENT SUBJECT X (d) Examine the STUDENT table: (3 marks)
(i) On which column (attribute) other than the primary key might you put an index. (1 line)
student-name
(ii) Why? (2 lines)
So that the table can be accessed via student-name, not just student-ID.
This will speed up [real-world] processing.
(iii) Why must the aggregate-score column be optional? (that is, why must it allow for a null value to be stored?) (3 lines)
Before the exams, there is no TEE score to store. The STUDENT record, however, needs to be in the database so that the required STUDENT SUBJECT record can be put into the database.
(e) Add the following data to the four tables: (7 marks)
(i) JOHN MURPHY and MARY KANTOR are enrolled in Information Systems. The have school marks of 50 and 52.
(ii) SAMMY LEE, a student at WA HIGH applies to sit for the TEE. His student-ID will be 1699. He was born on 18th December 1979.
(iii) SAMMY LEE is the first student to be enrolled in the new subject "Asian Culture". The exam date has been set for 11th November 1997. His school mark is currently unavailable.
(iv) JANE SMITH is a mature age student (born 14 March 1964) sitting Information Systems this year but she is not enrolled in any school.
NOTE:
- You may not change the structure of the database.
- You may leave null a column where there are missing details only if this is permitted in the TEE database, otherwise invent suitable data.
- You are not required to complete every blank row in the table.
STUDENT student-ID student-name date-of-birth school-name aggregate-score 1003 JOHN MURPHY 12/04/1980 WA HIGH null 1452 MARY KANTOR 17/03/1980 ST JUDES null 1699 SAMMY LEE 18/12/1979 WA HIGH null 1700 JANE SMITH 14/3/1964 NOSCHOOL null |
SCHOOL school-name address phone principal WA HIGH 23 Collins Terrace, Perth 08 9236 7890 George Lisson ST JUDES 145 Main St, Castleton 08 9371 5644 June Cotton NOSCHOOL null null null |
TEE SUBJECT subject-ID subject-name exam-date INFOSYS Information Systems 12/11/1997 ECON Economics 15/11/1997 GEOG Geography 23/11/1997 ACULT ASIAN CULTURE 11/11/1997 |
STUDENT SUBJECT student-ID subject-ID exam-mark school-mark 1003 GEOG null 56 1003 ECON null 78 1452 GEOG null 80 1452 ECON null 68 1003 INFOSYS null 50 1452 INFOSYS null 52 1699 ACULT null null 1700 INFOSYS null null (f) MARY KANTOR telephones the TEE administration office and wants to know the dates of all her TEE examination. Explain how the database tables would be accessed to get the required information. (12 lines) (4 marks)
Your answer should describe:
- the order in which the tables are accessed
- the key(s) used
- the number of records read at each stage
- the data retrieved
The DBMS would:
- Access the STUDENT table on student-name and get her Student-ID.
(One record retrieved each time.)- Access the STUDENT SUBJECT table on the student-ID and get all the subject-IDs.
(Multiple records retrieved (three).)- For each subject-ID retrieved in 2., access the SUBJECT table and pick up the exam-date and subject-name.
(One record retrieved.)
Table Access key Access key value No of records retrieved Attribute retrieved Attribute value 1 STUDENT STUDENT-NAME MARY KANTOR 1 STUDENT-ID 1452 2 STUDENT-SUBJECT STUDENT-ID 1452 3 SUBJECT-ID GEOG SUBJECT-ID ECON SUBJECT-ID INFOSYS 3 SUBJECT SUBJECT-ID GEOG 1 EXAM-DATE 23/11/1997 4 SUBJECT SUBJECT-ID ECON 1 EXAM-DATE 15/11/1997 5 SUBJECT SUBJECT-ID INFOSYS 1 EXAM-DATE 12/11/1997 END OF 1997 PART C
1998 PART C Extended Answers
Question 32 [19 marks]
THE WESTERN DOG ASSOCIATION General
The Western Dog Association is a fictitious non-profit association looking after the interests of pedigree dogs in Western Australia. The Western Dog Association is concerned only with the interests of pedigree dogs. Western Dog Association is affiliated with the National Dog Association (NDA). Membership of the NDA automatically results in membership of the relevant State body, in this case the Western Dog Association. Up to now, owners of mixed breeds have not been accepted as members. The Western Dog Association has an office in Perth, which requires a relational database to keep track of the people and dogs they deal with. All processing of subscriptions and registration of pedigrees are handled solely by the National Dog Association (NDA) from their head office in Melbourne.Dogs
A pedigree dog is a dog that is registered with the NDA, having satisfied their strict criteria for registration as pedigreed. All pedigree dogs belong to a Breed (e.g. Dalmatian, German Shepherd, Maltese Terrier, et cetera). Dogs have a pedigree name that may be different from the name by which their owner usually call them (e.g. his owner calls the Dalmatian Count Roger of Dalkinghurst: Spot).Licensed dog breeders hold a kennel licence. A holder of a kennel licence breeds only pedigree dogs. No dog can be considered as pedigreed if it was not bred by someone holding a kennel licence.
The Western Dog Association appoints someone locally as a contact person for each breed and needs to keep their names and telephone numbers on file.
Each pedigree dog registered with the NDA has a unique pedigree dog identifier—dog#. Data such as the dogs two names, date of birth and gender need to be recorded. A dog has only one registered owner with the NDA at any one time and the NDA wishes to record this but does not need to keep records of a dogs prior owners.
Membership
Owners pay subscription fees to belong to the NDA and thus the Western Dog Association. These are processed through the NDAs Melbourne office which allocates them a membership#. One membership subscription covers any number of pedigreed dogs the member might own. Periodically, the NDA sends the Western Dog Association a list of paid-up members, including their names, addresses and phone numbers and the details of the pedigree dogs registered to them. The Western Dog Association office uses this list to update their records.Obedience Training Classes
The Western Dog Association sponsors dog-training classes. The Association keeps names and addresses of trainers who conduct obedience classes for dogs. Only paid-up Association members may enrol their dogs in these classes. Trainers run weekly classes at various time and locations around the state and the Association keeps track of enrolments of dogs in these classes. Unfortunately, due to a scarcity of qualified trainers, dogs may only be enrolled in one class at a time.Each class has a unique ClassID. The Association only keeps records of the current obedience class enrolments. It has no need to be able to look up past enrolments. Any breed of pedigree dogs can take part in these obedience classes but many of the dogs are German Shepherds. Owners who want to enrol their dog in an obedience class first contact the Association. They want to know the cost, and where and when the classes are held. They also need a telephone number to contact the appropriate trainer.
a) Complete the entity relationship diagram (ERD) that represents a design for a relational database to satisfy the needs of the Western Dog Association. Include two extra entities Owner and Breed and name any relationships they might have. Include the attributes of the Dog, Owner and Breed entities on your diagram. Underline Primary keys. Foreign keys show links to other entities (tables). Draw an ellipse around any foreign keys in your design. (1 page available) (9 marks)
(b) Give two examples of non-primary key attributes in the Class table that could benefit from an index and explain why. (3 marks)
choose from:
- day and/or time
- location
- trainer-name
- cost
any suitable reason involving selection criteria for querying this table.
(c) Describe how you would change the database design as it stands at the moment to allow the Association to efficiently answer inquiries from owners who want to know if there is room in a particular class for their dog. Classes are restricted to enroll a maximum of 30 dogs. (2 marks)
Either create a logical attribute Full for the entity Class. It can have a value of Y or N (or T or F);or create a numeric attribute which will let you enter the number of places Places taken or Places available for the entity Class.
NOTE: No marks if the design is not altered.(d) The Association has been approached by the Police to allow non-pedigree dogs to enrol in their obedience classes. The Committee has decided that this would be an excellent form of community service and is prepared to find extra trainers but does not want to have the expense of changing the design of the database to allow this. They would expect owners of non-pedigreed dogs to become paid-up members of the Association. How would you include training of non-pedigree dogs without changing the design of your database? (3 marks)
Either include data to register a Breed of Dog as (only) one of the following: Mutt, Mongrel, Bitsa, Heinz, non-ped, etc.Also include a kennel of none or unknown or something similar OR allow the kennel-name and breed foreign keys on Dog to contain nulls.
(e) With the extension of obedience classes to community members, many existing Association members have asked if they can now enrol their dogs in more than one class. Extra trainers have been employed to conduct obedience classes so this should now be possible. The current database makes no allowance for this. Which of the following three design changes is the most suitable to implement in a relational database to solve the new requirement? You must explain your choice to obtain credit. (2 marks)
Insert Diagram here.B) is the correct answer.
Insert an entity Enrolment between the entities of Dog and Class.Reverse the direction of the relationships. One dog can have many enrolments. One class can have many enrolments.
A) is also correct in the real world, but cannot be implemented directly in relational databases (or most other types).
C) is an incorrect decomposition of A).
END OF 1998 PART C
1999 PART C Extended Answers30. Jigsaw Library (18 marks)
Mrs Stephenson is retired now and spends her time running a jigsaw library for people in her suburb. She requires a database to run on her laptop computer to keep track of her jigsaw library. Your task is to design this database.She has over 500 jigsaws in stock. She allocates each one a unique jigsaw ID. She keeps details of the number of pieces in a puzzle, its date of addition to her collection, donor name if not purchased, purchase price if purchased, the title of the picture, and the manufacturers name. She categorises the condition of each jigsaw as Good, Satisfactory, Poor (1 or 2 pieces missing) or Unusable.
Mrs Stephenson lends jigsaws at no charge to her borrowers who are mainly relatives and friends. She allows the borrowers to keep a puzzle for a time they specify up to a maximum of two months. She keeps details of the borrowers names and addresses and contact phone numbers. She also records details of each jigsaw borrowed, including the jigsawID, borrower, date borrowed and the date due to be returned. You may assume that each borrowers name is unique.
When a borrower returns a jigsaw, Mrs Stephenson records the date returned. If the borrower has attempted to complete the puzzle, she asks them what the puzzles current conditon is. If this conflicts with the condition she has previously recorded, she changes the condition in her records.
Mrs Stephenson has a problem. Sometimes the borrowed jigsaw, categorised as Good or Satisfactory, is found to have some pieces missing. The borrower returns the puzzle and complains to Mrs Stephenson who would now like to be able to track the previous borrowers of the puzzle.
Mrs Stephenson would also like to be able to produce a list of all borrowers with overdue loans, their phone numbers, the jigsaw borrowed and the date it was due to be returned.
(a) Produce an Entity Relationship (E-R) diagram modelling a physical design for a relational database to satisfy Mrs Stephensons requirements outlined above. On your diagram:
(i) Name all entities, attributes and relationships.
(ii) Identify Primary Keys by underlining them (e.g. PersonID).
(iii) Identify Foreign Keys linking with other tables with the characters -FK after the attribute name (e.g. department-FK).
(iv) Identify any attributes that have null values permitted by including -NP after their name (e.g. Spouse-NP).
(v) Identify any attributes that have values restricted to a set of just a few possible values by including -R after their name (e.g. Month-R).
(vi) Combinations of primary keys, foreign keys, allowed nulls and restricted values may be valid (e.g. SportsClub-FK-R-NP). (0.75 page) (13 marks)
Read this as:
One (1) Jigsaw Takes part in Numerous (N) Loans.
One (1) Borrower Makes (Borrows) Many (M) Loans.
Name of Database Attributes JIGSAW JigsawID
DateOfAddition
Pieces
DonorName-NP
PurchasePrice-NP
Title
Manufacturer
Condition-R
(8 attributes)LOAN JigsawID-FK
Borrower-FK
Date Borrowed
Date Due
DateReturned-NP
Note: DateDue may be replaced by DateBorrowed in the compound primary key
(5 attributes)BORROWER BorrowerName
Address
Phone
(3 attributes)1 mark for anything that looks like an E-R diagram
2 marks for getting the correct entities and naming them
2 marks for including the attributes
2 marks for including the relationships (named and correct way round)
1 mark for primary key of JIGSAW and BORROWER
1 mark for primary key of LOAN (if only two attributes correct, give 0.5 mark)
1 mark for foreign keys (0.5 mark each on the LOAN table)
1 mark for identifying DateReturned as -NP
1 mark for identifying Donor and PurchasePrice as -NP
1 mark for identifying Condition as -R(b) Should Mrs Stephenson delete the record of a jigsaws loan after it has been returned? Explain why or why not. (2 marks)
No. So that she can find out who previously borrowed the puzzle.(c) Explain exactly how you would use the database to query the name and telephone number of a borrower with an overdue loan for JigsawID = 98 which was due back yesterday and still has not been returned. (3 marks)
Read the LOAN table for
- JigsawID = 98 and
- DateDue = yesterday and
- DateReturned = Null
to find the BorrowerName.
Then access the BORROWER table using the BorrowerName as the access key to find out the Phone number.
END OF 1999 PART C
2000 PART C Extended Answers
29. (20 marks)
BrekkyFeast Breakfast CerealsBrekkyFeast is a new company in the breakfast cereal market. They recently set up a relational database system to assist in storing nutritional information about their products. Some sample data has been recorded in the tables and is shown below.
PRODUCT PRODUCT_ID PRODUCT_NAME SERVING_SIZE ENERGY PROTEIN FAT CARBOHYDRATE FIBRE 111 Honey Pops 40 1730 5.1 1.0 88.8 3.6 112 Wheat Flakes 30 1550 7.1 0.6 6.5 6.5 113 Crispy Rice 45 1680 6.8 1.1 4.8 4.8 114 Rice Balls 35 1460 6.7 0.8 5.3 5.3
INGREDIENT INGREDIENT_IDINGREDIENT_NAME SUPPLIER_NAME 001 RiceOrd Rice Company 002 SugarSweetness Unlimited 003 HoneyForest Products 004 WheatWestern Wheat Board
PRODUCT-INGREDIENT PRODUCT_ID INGREDIENT_ID 111 001 111 002 112 002 112 003 112 004
PACKAGING BARCODE PRODUCT_ID PACKAGE_SIZE SERVINGS 9 310333 061237 111 400 13 9 310333 092345 111 600 18 9 310333 021173 111 750 21 9 300743 006933 112 600 16 9 300743 003444 112 800 20
LEGEND Attribute Unit of Measurement Energy kilojoules/100 grams Protein grams/100 grams Fat grams/100 grams Carbohydrate grams/100 grams Fibre grams/100 grams Serving-Size grams Package-Size grams Servings per package (a) Draw an entity-relationship diagram in the frame below to represent the database design, including attributes and relationships. It is not necessary to identify the foreign keys.
You may assume that any product can be in more than one size. (space of one page) (7 marks)
(b) For each table listed below, complete the grid giving details of the primary key, each foreign key (if any) and the table(s) it links to. (5 marks)
0.5 mark each cell
Table Primary
KeyForeign
Key 1Linking to
TableForeign
Key 2Linking to
TablePRODUCT PRODUCT_ID INGREDIENT INGREDIENT_ID PRODUCT-
INGREDIENTPRODUCT_ID
INGREDIENT_IDPRODUCT_ID PRODUCT INGREDIENT_ID INGREDIENT PACKAGING BARCODE PRODUCT_ID PRODUCT (c) If supplies of ingredients were to be obtained from more than one supplier, the current database design would have to change. Describe clearly how you would change the current database design to allow an ingredient to be supplied by more than one supplier, and for a supplier to supply more than one ingredient. (10 lines) (4 marks)
1 mark per stepi. A new table called SUPPLIER should be created with a key of SUPPLIER_ID and also contains the field SUPPLIER_NAME.ii. The INGREDIENT table no longer has SUPPLIER_NAME as a field.iii. As there is a many to many relationship between SUPPLIER and INGREDIENT, another table (INGREDIENT_SUPPLIER) would be created to implement this relationship.
iv. The new table would only have the fields INGREDIENT_ID and SUPPLIER_ID.
These would form a compound key.(d) The Australian Health Society has recently asked BrekkyFeast for information about products containing wheat. BrekkyFeast wish to produce a report listing the PRODUCT_ID, PRODUCT_NAME and SERVING_SIZE for all products that contain wheat, to make this information available to people with gluten intolerance. Explain how the database tables would be accessed to get the required information, supporting your explanation with data from the table. (10 lines) (4 marks)
1 mark per step and a mark for the data
i. The INGREDIENT table is looked up to get the INGREDIENT_ID for wheat (004)ii. This is used to look up PRODUCT_INGREDIENT table to determine the PRODUCT_IDs of products that contain wheat. (112)
iii. These PRODUCT_IDs can then be used to obtain the rest of the required information from the PRODUCT table. (Wheat Flakes, 30g)
END OF 2000 PART C
2001 PART C Extended Answers
END OF 2001 PART C