sql数据库知识点

网站编辑2023-05-09 16:38:18473

SQL是一种常用的关系型数据库管理系统,它用于存储和管理数据。在学习SQL之前,以下是一些关于SQL的一般知识点:

1. SQL命令: - "SELECT * FROM table1" - "SELECT COUNT(*) FROM table2" - "INSERT INTO table1 LOAD table2" - "UPDATE table1 WHERE table2.name = 'Table1'" - "DELETE INSERT INTO table2 DELETE" - "UPDATE INSERT INTO table1 FALSE" - "UPDATE INSERT INTO table2 WHERE table2.name = 'Table2'"

2. 数据类型: - 数据类型包括整数(数字)、浮点数(小数)、布尔值(布尔值)、字符串(字符串)、字符串(数字)、数组(数组)、集合(集合)、多维数据类型(多维数据类型)、嵌套类型(嵌套类型)、聚合类型、函数(函数类型)、日期和时间类型以及其他类型。

3. 数据操作: - 删除和插入数据: - 更新数据: - 删除数据: - 插入数据:

4. SQL语言: - SELECT * FROM table1 WHERE table2.name = 'Table2' - DELETE INSERT INTO table1 DELETE - UPDATE table1 WHERE table2.name = 'Table1' - UPDATE INSERT INTO table1 FALSE - DELETE INSERT INTO table2 DELETE - "INSERT INTO table1 INTEGER WHERE table2.id = '1'" - "INSERT INTO table1 INTEGER WHERE table1.name = 'Table2'" - "INSERT INTO table1 DELETE "INSERT INTO table1" - "UPDATE INSERT INTO table1 FALSE" - "UPDATE INSERT INTO table1" - "DELETE INSERT INTO table1 FALSE" - "UPDATE INSERT INTO table1 WHERE table2.name = 'Table1'" - "DELETE INSERT INTO table2 FALSE"

5. 数据查询: - 简单查询: - GROUP BY A WHERE A B = DATE_FORMAT ( - DELETE INSERT INTO GROUP BY A - UPDATE INTO GROUP BY A - INSERT INTO A WHERE A B = DATE_FORMAT - INSERT INTO A A WHERE A B = DATE_FORMAT - DATE_FORMAT ( - INSERT INTO A INTEGER - UPDATE INTO A INTEGER - INSERT INTO DATE_FORMAT - DELETE INSERT INTO A B - UPDATE INTO A DATE_FORMAT - INSERT INTO A WHERE A B = DATE_A2 - INSERT INTO B WHERE B = DATE_B1 - INSERT INTO A CROSS - UPDATE INTO A INTEGER - INSERT INTO DATE_FORMAT - DELETE INSERT INTO A DELETE - UPDATE IN