检索数据

Oracle SQL 入门

Sara Billen

Curriculum Manager

自定义输出

交叉的扳手和螺丝刀

去重
字符串操作
算术表达式
数据排序

DISTINCT

SELECT BillingCountry
FROM Invoice

| BillingCountry |
|----------------|
| Germany        |
| Germany        |
| USA            |
| Norway         |
| ...            |

* 选中 412 行

SELECT DISTINCT BillingCountry
FROM Invoice

| BillingCountry |
|----------------|
| Germany        |
| Norway         |
| USA            |
| ...            |

* 选中 24 行

字符串操作——连接运算符

SELECT FirstName || LastName
FROM Customer

| FirstName || LastName       |
|-----------------------------|
| FrankHarris                 |
| HannahSchneider             |
| LucasMancini                |
| ...                         |

字符串操作——字符常量

SELECT 'Full name: ' || FirstName || ' ' || LastName
FROM Customer

| 'Full name: ' || FirstName || ' ' || LastName |
|-----------------------------------------------|
| Full name: Frank Harris                       |
| Full name: Hannah Schneider                   |
| Full name: Lucas Mancini                      |
| ...                                           |

字符串操作——替代引号运算符

SELECT LastName || ': This employee's title is: ' || Title
FROM Employee

syntax error at or near "title"
LINE 1: SELECT LastName || ': This employee's title is: ' || Title

字符串操作——替代引号运算符

SELECT LastName || q'[: This employee's title is: ]' || Title
FROM Employee

| LastName || q'[, this employee's title is: ]' || Title |
|--------------------------------------------------------|
| Adams: This employee's title is: General Manager       |
| Edwards: This employee's title is: Sales Manager       |
| Park: This employee's title is: Sales Support Agent    |
| King: This employee's title is: IT Staff               |
| ...                                                    |

算术表达式

使用算术运算符对"数值"和"日期"创建表达式。

运算符	说明
+	加法
-	减法
*	乘法
/	除法

算术表达式

SELECT TrackName, Milliseconds, Milliseconds / 1000
FROM Track

| TrackName                | Milliseconds | Milliseconds / 1000 |
|--------------------------|--------------|---------------------|
| Killer Queen             | 182099       | 182.099             |
| Smells Like Teen Spirit  | 301296       | 301.296             |
| The Star Spangled Banner | 43232        | 43.232              |
| With Or Without You      | 299023       | 299.023             |

排序行

SELECT LastName, Title, City, HireDate 
FROM Employee
ORDER BY HireDate

| LastName | Title                 | City       | HireDate            |
|----------|-----------------------|------------|---------------------|
| Peacock  | Sales Support Agent   | Calgary    | 2002-04-01 00:00:00 |
| Edwards  | Sales Manager         | Calgary    | 2002-05-01 00:00:00 |
| Adams    | General Manager       | Edmonton   | 2002-08-14 00:00:00 |
| Park     | Sales Support Manager | Calgary    | 2003-05-03 00:00:00 |
| Johnson  | Sales Support Agent   | Calgary    | 2003-10-17 00:00:00 |
| Mitchell | IT Manager            | Calgary    | 2003-10-17 00:00:00 |
| King     | IT Staff              | Lethbridge | 2004-01-02 00:00:00 |
| Callahan | IT Staff              | Lethbridge | 2004-03-04 00:00:00 |

排序行

按降序排序：

SELECT LastName, Title, City, HireDate 
FROM Employee
ORDER BY HireDate DESC

按多列排序：

SELECT LastName, Title, City, HireDate 
FROM Employee
ORDER BY City, HireDate

¡Vamos a practicar!

Oracle SQL 入门