Between…And
用途：
指定需返回数据的范围
语法：
SELECT column_name FROM table_name WHERE column_name BETWEEN value1 AND value2 |
例：
“Persons”表中的原始数据
|
LastName |
FirstName |
Address |
City |
|
Hansen |
Ola |
Timoteivn 10 |
Sandnes |
|
Nordmann |
Anna |
Neset 18 |
Sandnes |
|
Pettersen |
Kari |
Storgt 20 |
Stavanger |
|
Svendson |
Tove |
Borgvn 23 |
Sandnes |
用BETWEEN…AND返回LastName为从”Hansen”到”Pettersen”的数据：
SELECT * FROM Persons WHERE LastName BETWEEN 'Hansen' AND 'Pettersen' |
返回结果:
|
LastName |
FirstName |
Address |
City |
|
Hansen |
Ola |
Timoteivn 10 |
Sandnes |
|
Nordmann |
Anna |
Neset 18 |
Sandnes |
|
Pettersen |
Kari |
Storgt 20 |
Stavanger |
为了显示指定范围之外的数据，也可以用NOT操作符：
SELECT * FROM Persons WHERE LastName NOT BETWEEN 'Hansen' AND 'Pettersen' |
返回结果:
|
LastName |
FirstName |
Address |
City |
|
Svendson |
Tove |
Borgvn 23 |
Sandnes |
Distinct
用途：
DISTINCT关键字被用作返回唯一的值
语法：
SELECT DISTINCT column-name(s) FROM table-name |
解释：
当column-name(s)中存在重复的值时，返回结果仅留下一个
例：
“Orders”表中的原始数据
|
Company |
OrderNumber |
|
Sega |
3412 |
|
W3Schools |
2312 |
|
Trio |
4678 |
|
W3Schools |
6798 |
用DISTINCT关键字返回Company字段中唯一的值：
SELECT DISTINCT Company FROM Orders |
返回结果:
|
Company |
|
Sega |
|
W3Schools |
|
Trio |
|
SQL的详细语法介绍——对于学习数据库最基础知识三
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