SQL超基础内容——2.很简单的内容

以mysql自带的world数据库为例说明以下最常用

world结构

city结构

SELECT

选取

SELECT id,name 
FROM WORLD.CITY

WHERE

条件

SELECT id,name,population
FROM WORLD.CITY
WHERE Population >= 600000

AND&OR

SELECT *
FROM WORLD.CITY
WHERE Population >= 600000 and countrycode = 'AUS';
SELECT *
FROM WORLD.CITY
WHERE Population >= 600000 or countrycode = 'AUS';

and&or

ORDER BY

可以针对数字排序，也可以对文本排序，甚至可以针对多个条件排序（以逗号,分隔）

SELECT *
FROM WORLD.CITY
WHERE Population >= 600000
ORDER BY population

以population从低到高排序
由高到低排序为

ORDER BY population desc

INSERT

插入

INSERT INTO world.city VALUES (19989,'test','AFG','kabol','100000');
INSERT INTO world.city (ID,NAME,COUNTRYCODE) VALUES (19899,'test','AFG')

UPDATE

UPDATE world.city SET id = 19898 WHERE id = 19899

DELETE

DELETE FROM world.city WHERE id = 19899

SQL超基础内容——2.很简单的内容

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