限制数据

Oracle SQL 入门

Sara Billen

Curriculum Manager

筛选行

比较运算符
比较关键字
逻辑运算符

WHERE

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

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

比较运算符

运算符	说明
>	大于
>=	大于或等于
<	小于
<=	小于或等于
=	等于
<>	不等于

SELECT UnitPrice
FROM Track
WHERE UnitPrice <> 0.99

比较关键字

更多 WHERE 子句功能

比较关键字 - 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       |
| ...                              |

比较关键字 - 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          |

比较关键字 - LIKE

使用 LIKE 按字符模式选择行

符号	说明
`%`	表示任意长度（含0）的字符序列
`_`	表示任意单个字符

比较关键字 - LIKE

SELECT LastName
FROM Employee
WHERE LastName LIKE '_a%'

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

逻辑运算符

逻辑运算符 - 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  |

逻辑运算符 - 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  |
| ...                                |

逻辑运算符 - 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 |
| ...                                |

回顾

WHERE：按条件筛选行

比较运算符：=, <, >, <=, >=, <>
比较关键字：BETWEEN, IN, LIKE
逻辑运算符：AND, OR, NOT

Passons à la pratique !

Oracle SQL 入门