3. 3
SQL Aliases
SQL aliases are used to give a table, or a column in a table,
a temporary name. Aliases are often used to make column
names more readable. An alias only exists for the duration
of that query. An alias is created with the AS keyword.
4. 4
Table Name: Students
Student_I
D
Firstname Lastname Age Allowance
1100 Fernan Cabuso 22 400
1101 Joshua Guimaras 22 500
1102 Joyce Hisona 21 500
1103 Andrea Laki 20 600
Example: Alias
SELECT Student_ID AS ID
FROM Students
5. 5
Table Name: Students
Student_I
D
Firstname Lastname Age Allowance
1100 Fernan Cabuso 22 400
1101 Joshua Guimaras 22 500
1102 Joyce Hisona 21 500
1103 Andrea Laki 20 600
Example: Alias
Select Student_ID as ID, Firstname as Pangalan
from Employees
6. 6
The SQL LIKE Operator
The LIKE operator is used in a WHERE clause to search for a
specified pattern in a column.
There are two wildcards often used in conjunction with
the LIKE operator:
• The percent sign (%) represents zero, one, or multiple characters
• The underscore sign (_) represents one, single character
• The percent sign and the underscore can also be used in
combinations!
7. 7
LIKE Operator Description
WHERE Student_Name LIKE 'a%' Finds any values that start with "a"
WHERE Student_Name LIKE '%a' Finds any values that end with "a"
WHERE Student_Name LIKE
'%or%'
Finds any values that have "or" in any position
WHERE Student_Name LIKE '_r%' Finds any values that have "r" in the second position
WHERE Student_Name LIKE 'a_%'
Finds any values that start with "a" and are at least 2
characters in length
WHERE Student_Name LIKE
'a__%'
Finds any values that start with "a" and are at least 3
characters in length
WHERE Student_Name LIKE 'a%o' Finds any values that start with "a" and ends with "o"
Here are some examples showing different LIKE operators with '%' and '_' wildcards:
8. 8
Example: LIKE Operator
The following SQL statement selects all records in
Students Table with a FirstName starting with “J".
We use the following LIKE statement:
9. 9
Table Name: Students
Student_I
D
Firstname Lastname Age Allowance
1100 Fernan Cabuso 22 400
1101 Joshua Guimaras 22 500
1102 Joyce Hisona 21 500
1103 Andrea Laki 20 600
Example: Like
SELECT *
FROM Students
WHERE FirstName LIKE ‘J%’;
10. 10
The following SQL statement selects all
records in Students Table with a LastName
ending with “s". We use the following LIKE
statement:
11. 11
Table Name: Students
Student_I
D
Firstname Lastname Age Allowance
1100 Fernan Cabuso 22 400
1101 Joshua Guimaras 22 500
1102 Joyce Hisona 21 500
1103 Andrea Laki 20 600
Example: Like
SELECT *
FROM Students
WHERE Lastname LIKE ‘%s’;
12. 12
The following SQL statement selects all
records in Students Table with Firstname
that have “Jo” in any position. We use the
following LIKE statement:
13. 13
Table Name: Students
Student_I
D
Firstname Lastname Age Allowance
1100 Fernan Cabuso 22 400
1101 Joshua Guimaras 22 500
1102 Joyce Hisona 21 500
1103 Andrea Laki 20 600
Example: Like
SELECT *
FROM Persons
WHERE City LIKE ‘%Jo%’;
14. 14
The following SQL statement selects all
records in Students Table with a Firstname that
have “O” in the second position. We use the
following LIKE statement:
15. 15
Table Name: Students
Student_I
D
Firstname Lastname Age Allowance
1100 Fernan Cabuso 22 400
1101 Joshua Guimaras 22 500
1102 Joyce Hisona 21 500
1103 Andrea Laki 20 600
Example: Like
SELECT *
FROM Students
WHERE FirstName LIKE ‘_O%’;
16. 16
The following SQL statement selects all
records in Students Table with a Firstname
that starts with “j” and ends with “a”. We
use the following LIKE statement:
17. 17
Table Name: Students
Student_I
D
Firstname Lastname Age Allowance
1100 Fernan Cabuso 22 400
1101 Joshua Guimaras 22 500
1102 Joyce Hisona 21 500
1103 Andrea Laki 20 600
Example: Like
SELECT *
FROM Students
WHERE FirstName LIKE ‘j%a’;
18. 18
The following SQL statement selects
all records in Students Table with a
Firstname that does not starts with “j”.
We use the following LIKE statement:
19. 19
Table Name: Students
Student_I
D
Firstname Lastname Age Allowance
1100 Fernan Cabuso 22 400
1101 Joshua Guimaras 22 500
1102 Joyce Hisona 21 500
1103 Andrea Laki 20 600
Example: Like
SELECT *
FROM Students
WHERE FirstName NOT LIKE ‘j%’;
