Section 11
(Answer all questions in this section)
1. Column integrity refers to
Columns always having values
Columns always containing positive numbers
Columns always containing values consistent with the defined data format
Columns always containing text data less than 255 characters
2. One or more columns in a primary key can be null. True or False?
True
False
3. The explanation below is an example of what constraint type:
The value in the dept_no column of the EMPLOYEES table must match a value in the dept_no column in the DEPARTMENTS table.
Entity integrity
Referential integrity
Column integrity
User-defined integrity
4. A foreign key always refers to a primary key in the same table. True or False?
True
False
5. Foreign keys cannot be null when
It is part of a primary key
It refers to another table
It contains three or more columns
6. A table does not have to have a primary key. True or False?
True
False
7. The explanation below defines which constraint type:
A primary key must be unique, and no part of the primary key can be null.
Entity integrity
Referential integrity
Column integrity
User-defined integrity
8. Identify all of the correct statements that complete this sentence: A primary key is ...(Choose Three)
(Choose all correct answers)
A single column that uniquely identifies each row in a table
A set of columns that uniquely identifies each row in a table
A set of columns and keys in a single table that uniquely identifies each row in a single table
Only one column that cannot be null
9. The explanation below defines which constraint type:
A column must contain only values consistent with the defined data format of the column
Entity integrity
Referential integrity
Column integrity
User-defined integrity
10. The explanation below is an example of what constraint type:
If the value in the balance column of the ACCOUNTS table is below 100, we must send a letter to the account owner which will require extra programming to enforce.
Entity integrity
Referential integrity
Column integrity
User-defined integrity