摘要: ## 列属性 | Column Name | Datatype | PK | NN | AI | Default | | | | | | | | | Customer_id | INT | √| √| √| | | first_name | VARCHAR(50) | |√ | | | | birt 阅读全文
posted @ 2023-05-23 23:53 ganwong99 阅读(37) 评论(0) 推荐(0)
摘要: ## 内连接 INNER JOIN 内联接使用比较运算符根据每个表共有的列的值匹配两个表中的行。 ```sql { SELECT order_id,o.customer_id,first_name,last_name FROM orders o JOIN customers c ON o.custo 阅读全文
posted @ 2023-05-23 17:56 ganwong99 阅读(126) 评论(0) 推荐(0)
摘要: ## AND OR NOT ```sql { SELECT * FROM customers WHERE NOT (birth_date >'1990-01-01' OR points>1000 ); } ``` ## IN ```sql { SELECT * FROM products WHERE 阅读全文
posted @ 2023-05-23 15:14 ganwong99 阅读(10) 评论(0) 推荐(0)