第三章数据库题目

3.1 Name three sources for databases.

3.2 What is the basic premise of this and the next chapter?

3.3 Explain what is wrong with the table in Figure 3-2.

3.4 Define each of the terms listed in Figure 3-3.

3.5 Describe the characteristics of a table that make it a relation. Define the term domain and explain the significance of the domain integrity constraint to a relation.

3.6 Give an example of two tables that are not relations.

3.7 Suppose that two columns in two different tables have the same column name. What convention is used to give each a unique name?

3.8 Must all the values in the same column of a relation have the same length?

3.9 Explain the three different sets of terms used to describe tables, columns, and rows.

3.10 Explain the difference between functional dependencies that arise from equations and

those that do not.

3.11 Explain the intuitive meaning of the functional dependency.

PartNumber→PartWeight

3.12 Explain the following statement: “The only reason for having relations is to store instances of functional dependencies.”

3.13 Explain the meaning of the expression:

(FirstName, LastName) →Phone

3.14 What is a composite determinant?

3.15 If (A, B)→C , then can we also say that A→C?

3.16 If A →(B, C), then can we also say that A →B?

3.17 For the SKU_DATA table in Figure 3-1, explain why Buyer determines Department, but Department does not determine Buyer.

3.18 For the SKU_DATA table in Figure 3-1, explain why:

SKU_Description→(SKU, Department, Buyer).

3.19 If it is true that

PartNumber S PartWeight

does that mean that PartNumber will be unique in a relation?

3.20 Under what conditions will a determinant be unique in a relation?

3.21 What is the best test for determining whether a determinant is unique?

3.22 What is a composite key?

3.23 What is a candidate key?

3.24 What is a primary key? Explain the significance of the entity integrity constraint to a

primary key.

3.25 Explain the difference between a candidate key and a primary key.

3.26 What is a surrogate key?

3.27 Where does the value of a surrogate key come from?

3.28 When would you use a surrogate key?

3.29 What is a foreign key? Explain the significance of the referential integrity constraint to a

foreign primary key.

3.30 The term domestic key is not used. If it were used, however, what do you think it would

mean?

3.31 What is a normal form?

3.32 Illustrate deletion, modification, and insertion anomalies on the STUDENT_ACTIVITY

relation in Figure 3-24.