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62 bài trong 7 trang (10 bài/trang) và bạn đang ở trang 2.
Demo

Which of the following is not one of the five SQL built-in functions? A) MODE B) SUM C) COUNT D) MAX.... Which of the following commands are correct for adding a foreign key. A. Add foreign key did to table employees; B. Insert did into table employees; C. Alter table employees add foreign key (did) references department(did); D. Create foreign key (did) references department;.......

Demo

You are designing a database that will contain customer orders. Customers will be able to order multiple products each time they place an order. You review the database design, which is shown in the exhibit. You want to promote quick response times for queries and minimize redundant data. What should you do? A. (I) Create a new order table named OrderDetail. Add OrderID, ProductID, and Quantity columns to this table. B. Create a composite PRIMARY KEY constraint on the OrderID and ProductID columns of the Orders table. C. (II) Remove the ProductID and Quantity columns from the Orders table. D. Both A and C......

Demo

A table with no repeating groups, with a single field primary key , and with a transitive dependency violates which normal form ? a. Second normal form b. Third normal form c. First normal form d. Second normal form and third normal form........ Going from first to second normal form removes a. Transitive dependencies b. Data redundancy c. Full functional dependencies d. Functional dependencies .....

Demo

Which one of the following is correct? a. All functional dependencies are many-to-many relationships. b. All functional dependencies are many-to-one relationships. c. All functional dependencies are one-to-one relationships. d. None of the above are true. ... Given the functional dependencies (AB -> C, C -> D) for the relation schema R(ABCD), the dependency A -> D can be inferred by a. the reflexive rule b. the augmentation rule c. the transitve rule d. none of the above ......

Demo

Consider the relation student(sno, sname, cname, cno) where (sno, cno) or (sname, cname) are candidate keys. There are functional dependencies within the keys. The highest normal form whose requirements this relation satisfies is: a. 1NF b. 2NF c. 3NF d. BCNF....... For a table to be in first normal form (1NF), it must a. No have any foreign keys. b. Have at least one foreign key. c. Not have any repeating groups. d. Have a composite primary key.......

Demo

Table TT{A, B, C, D, E, F} and a set of functional dependencies A,C,E->D,F; B->C,D,F; A->B,C,F; The closure of {A D} is: a. A B C D F b. A B C D E c. E B C D F d. A E C D F........ Table TT{A, B, C, D, F,G, H} and a set of functional dependencies A,B->G,H; F->A,B,C; C,G- >D,H; C,D,F->G; A,B,H->F; The closure of {C G} is: a. CGD b. BGDH c. CGDH d. AGDH.....

Demo

Nulls, if used improperly, can create problems because they can represent: a. An unknown attribute value. b. A known, but missing, attribute value. c. A "not applicable" condition. d. All of the above..... SELECT C1.CustName, C1.SalesRepNo FROM CUSTOMER C1; the "C1" is called a(n) ________________ . a. term b. alias c. convention d. phrase.......

Demo

The way an end user views the database is called_________? a. Conceptual Schema b. Internal Schema c. Logical Scheme d. External Schema..... Which of the following terms is synonymous with "relation"? a. Attribute b. Table c. Record d. Tuple.... When the primary key of one relation is placed into a second relation, it is called a: a. field key. b. referential integrity......

Demo

A field in a table has the value NULL . This can mean the data is…… a. missing b. nonexistent c. not applicable d. all of the others...... A composite primary key can be defined the CONSTRAINT phrase in which SQL commands? a. Changed Table b. Create Table c. Build Table d. Modify Table.....

Demo

The number of entity classes in a relationship is know as the relationships: a. degree b. maximum cardinality c. cordiality d. minimum cardinality..... In Hierarchical database model _______ are used to relate parent and children a. No relation sign b. Dollars c. Pointers d. Line.......

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