This document covers database concepts including select operations, projection, arithmetic operators, operator precedence, null values, column aliases, and assignment questions involving queries. It discusses selecting specific and multiple columns, using arithmetic operators like addition and subtraction, enforcing operator precedence with parentheses, null values in expressions, and renaming columns with aliases. It provides examples of queries to display concatenated name and job, filter for a department number, and select name and salary by job title.

1. Database Systems
Administration
Lab #:02

2. Select operation-No Projection

3. Projection(Selecting Specific Columns)

4. Projection
(Selecting Multiple Columns ..Cont.)

5. Projection
(Selecting Multiple Columns ..Cont.)

6. Projection with Selection
using WHERE Clause

7. Arithmetic Operators
Operator Description
+ Add
- Subtract
* Multiply
/ Divide

8. Using Arithmetic Operators

9. Operator Precedence
* / + -
• Multiply and division take priority over addition and subtraction
• Operators of the same priority are evaluated from left to right.
• Parentheses are used to force prioritized evaluation.

10. Operator Precedence
Notice that
multiplication is
performed before
addition

11. Using Parentheses
You can enforce the
rules of precedence by
using the parenthesis

12. Null Values
NULL Value:
• Unavailable Value
• Unassigned Value
• Unknown Value
• Inapplicable Value
Null Value

13. Null Values in Arithmetic Expression
Arithmetic expression
containing a Null Value
evaluates to null

14. Column Aliases
• Renames a column heading
• Aliases immediately follows column
names.
• Optional AS keyword between column
name and aliases.
• Requires double quotation marks if it
contains spaces or special characters or
is case sensitive

15. Using Column Aliases

16. Assignment 02
1. Display the name concatenated with the
job, separated by comma and space also
name the column with Employee and Title.
2. Display the name and job of the employee
, they belongs to department number 20.
3. Display the name and salary of the person
whose job title is MANAGER.