DBS201
SQL Practice Problems
Sample questions and SQL answers:
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Use the following sample tables, data, and constraints to answers the questions that follow:
EMP
EMP_NUM
EMP_FNAME
EMP_LNAME
JOB_CLASS
HIREDATE
101
John
News
DBD
1-NOV-78
102
David
Senior
SYA
3-OCT-88
103
June
Arbough
EEG
23-JUN-99
104
Anne
Ramoras
SYA
30-FEB-92
105
Alice
Johnson
DBD
15-AUG-95
106
William
Smithfield
PRG
31-OCT-02
114
Annelise
Jones
118
default value
Frommer
JOB
JOB_CODE
JOB_CLASS
CHG_HOUR
APD
Application Designer
DBD
Database Designer
EEG
Elec. Engineer
$84.50
GSP
General Support
$18.36
PRG
Programmer
$37.75
SYA
Systems Analyst
$96.75
PROJECT
PROJ PROJ
_NUM _NAME
15
Evergreen
18
Amber Wave
$48.10
$105.00
PROJ_EMP
PROJ
EMP
_NUM _NUM HOUR
15
103
23.8
15
101
19.4
15
105
35.7
18
114
24.6
18
118
25.3
A) Create/Alter/Drop Table Commands (Data Definition Language):
1.
All employees may or may not be given a job_class. Job_class can be repeated in the
employee table. If no first name is specified when inserting an employee record, then a default
of "unknown" will be entered. All employees must have a last name, a hiredate, and the
hiredate must be >= 1-Jan-1990.
Complete the data dictionary below: Table: EMPLOYEE
Column
Type
Len
gth
Emp_Num
emp_fname
emp_lname
Job_Class
hiredate
PK
FK
Required
Not Null
Unique
Validation
/Check
Default
Complete the data dictionary below: Table: JOB
All chg_hour will default to a value of $15/hour if no value is specified during the insert. If a
value is specified, then it must be >= $15.
Column
Type
Len
PK
FK
gth
Required
Unique
Not Null
Validation
Default
/Check
job_code
job_class
chg_hour
3.
Create the EMP table from the sample data on the previous page. Also implement the
following constraints.
Column
Type
Len
PK
FK
gth
Emp_Num
int
emp_fname
char
20
emp_lname
char
20
Job_Class
char
3
Required
Unique
Not Null
Validation
Default
/Check
PK
unknown
NN
unique
job
(job_code)
hiredate
date
NN
>=1/1/1990
4.
Create the JOB table from the sample data on the previous page. Also implement the
following constraints.
Column
Type
Len
PK
gth
job_code
char
3
job_class
char
30
chg_hour
decimal
5,2
FK
Required
Not Null
Unique
Validation
Default
/Check
PK
>=15
15
5.
Add a new attribute to the JOB table named OvertimeCharge that must always have a value.
6.
Add a constraint to the JOB table that will ensure all CHG_HOUR data is >= 25.
7.
Add a constraint that will add the value NA to all JOB_CLASS columns if no value is
specified when the record is inserted into the table.
8.
Add a constraint that always requires a value entered into the CHG_HOUR column.
9.
Change the CHG_HOUR column to store numbers up to 12 digits in length (including
decimal points).
10.
Drop the constraint CHARGE_CK from the CHG_HOUR column.
11.
Drop the column named OvertimeCharge from the JOB table.
12.
Drop the chg_hour column and all of it's data from the job table.
13.
Remove the job table and all of it's data.
14.
Drop the table emp and all rows of it's data.
B) Data Manipulation Commands:
1.
Insert the last 3 rows shown into the EMP table.
2.
Update the employee fname to Jim instead of James for employee 118
3.
Update the Database Designer chg_hour value by 10%
4.
Remove the row from the job table for job code PRG
5.
Remove the JOB table and all of it's data
6.
Remove the employees from the employee table where the hiredate is before 1-Jan-90
7.
Remove the emp table and all of it's data
C) Select Commands:
1.
Show the employee first and last names and their job class description and hourly charge.
2.
Same question as above, but only show the records where the chg_hour is <100
3.
Select the hours worked and lastname and hiredate for all employees.
4.
Create a view called: WORK_INFO which will select the hours worked and lastname and
hiredate for all employees hired before 1-jan-02.
5.
Select employee fname and lname and all projects that they are working on. Save this select
statement as a view called: EMP_PROJECTS
6.
Select employee fname and lname for every person working on project 18.
7.
Select all project names and job class descriptions that the project requires. Save this select
statement as a view called: EMP_JOB_SKILLS
8.
Select all project names and job class descriptions that the project requires for only the job
code of DBD. Save this statement as a view called: DATABASE_DESIGNERS
9.
Select customer first and last name, credit limit, and salesrep first and last name where the
credit limit is >= 1500.
Answers