Restricting data

Introduction to Oracle SQL

Sara Billen

Curriculum Manager

Filtering rows

Filter

Comparison operators
Comparison keywords
Logical operators

WHERE

SELECT FirstName, LastName, Country 
FROM Customer
WHERE Country = 'Portugal'

| FirstName | LastName  | Country  |
|-----------|-----------|----------|
| João      | Fernandes | Portugal |
| Madalena  | Sampaio   | Portugal |

Comparison operators

Operator	Description
>	Greater than
>=	Greater than or equal to
<	Less than
<=	Less than or equal to
=	Equal
<>	Not equal

SELECT UnitPrice
FROM Track
WHERE UnitPrice <> 0.99

Comparison keywords

Additional WHERE clause features

Comparison keywords - BETWEEN

SELECT Name, Milliseconds 
FROM Track
WHERE Milliseconds BETWEEN 100000 AND 200000

| Name              | Milliseconds |
|-------------------|--------------|
| Perfect           | 188133       |
| Right Through You | 176117       |
| We Die Young      | 152084       |
| Put You Down      | 196231       |
| ...                              |

Comparison keywords - IN

SELECT EmployeeId, LastName, Title
FROM Employee
WHERE EmployeeId IN (4, 5, 6)

| EmployeeId | LastName | Title               |
|------------|----------|---------------------|
| 4          | Park     | Sales Support Agent |
| 5          | Johnson  | Sales Support Agent |
| 6          | Mitchell | IT Manager          |

Comparison keywords - LIKE

Select rows that match a character pattern by using LIKE

Symbol	Description
`%`	Represents any sequence of zero or more characters
`_`	Represents any single character

Comparison keywords - LIKE

SELECT LastName
FROM Employee
WHERE LastName LIKE '_a%'

| LastName |
|----------|
| Park     |
| Callahan |

Logical operators

Logical operators - AND

SELECT InvoiceId, BillingCountry, Total
FROM Invoice
WHERE BillingCountry = 'Australia' 
      AND Total > 4

| InvoiceId | BillingCountry | Total |
|-----------|----------------|-------|
| 66        | Australia      | 5.94  |
| 250       | Australia      | 13.86 |
| 305       | Australia      | 8.91  |

Logical operators - OR

SELECT InvoiceId, BillingCountry, Total
FROM Invoice
WHERE BillingCountry = 'Australia' 
      OR Total > 4

| InvoiceId | BillingCountry | Total |
|-----------|----------------|-------|
| 3         | Belgium        | 5.94  |
| 4         | Canada         | 8.91  |
| 5         | USA            | 13.86 |
| 10        | Ireland        | 5.94  |
| ...                                |

Logical operators - NOT

SELECT InvoiceId, BillingCountry, Total
FROM Invoice
WHERE BillingCountry NOT IN ('Australia', 'Canada', 'United Kingdom')

| InvoiceId | BillingCountry | Total |
|-----------|----------------|-------|
| 1         | Germany        | 1.98  |
| 2         | Norway         | 3.96  |
| 3         | Belgium        | 5.94  |
| 5         | USA            | 13.86 |
| ...                                |

Recap

WHERE: filter rows based on a condition

Comparison operators: =, <, >, <=, >=, <>
Comparison keywords: BETWEEN, IN, LIKE
Logical operators: AND, OR, NOT

Let's practice!

Introduction to Oracle SQL