access数据库基础知识

网站编辑2023-05-04 10:15:40227

SQL是一种常用的关系型数据库管理系统,它是一种基于SQL语言的关系型数据库管理系统,用于管理和维护用户数据。SQL语言具有许多优点,包括易于操作、快速查询、安全性强、可靠性高等。以下是SQL的基本概念和用法:

1. SQL语法:

1) SELECT * FROM table1 WHERE table2 = table1 AND table3 = table2; 2) SELECT * FROM table2 ON table1 WHERE table2 = table3 ORDER BY name_rank(); 3) SELECT * FROM table1 WHERE table1 = NULL; 4) SELECT * FROM table2 WHERE table2 = NULL; 5) SELECT * FROM table3 WHERE table3 = NULL;

2. SQL查询语句:

1) SELECT * FROM table1 WHERE row_number = column_name_rank(); 2) SELECT * FROM table2 WHERE row_number = column_name_rank(); 3) SELECT * FROM table3 WHERE row_number = column_name_rank(); 4) SELECT * FROM table1 WHERE column1 = column_name_rank(); 5) SELECT * FROM table2 WHERE column2 = column_name_rank(); 6) SELECT * FROM table3 WHERE column3 = column_name_rank(); 7) SELECT * FROM table1 WHERE column1 = column_name_rank();

3. SQL视图:

1) SELECT * FROM table1 WHERE row_number = column_name_rank(); 2) SELECT * FROM table2 WHERE row_number = column_name_rank(); 3) SELECT * FROM table3 WHERE row_number = column_name_rank(); 4. SQL存储过程:

1) SELECT * WHERE column_name_rank() IN (3, 9, 5); 2) SELECT * WHERE column_name_rank() IN (10, 3, 9); 3) SELECT * WHERE column_name_rank() IN (20, 6, 10); 4) SELECT * WHERE column_name_rank() IN (30, 9, 11); 5) SELECT * WHERE column_name_rank() IN (40, 12, 9); 6) SELECT * WHERE column_name_rank() IN (45, 15, 20); 7) SELECT * WHERE column_name_rank() IN (60, 17, 10);

4. 查询语句:

1) FOR row_number (SUM(column_name), INVALID_column_name_rank()), SUM(column_name) >= 3:

```

2) FOR column_name_rank() IN (5, 7, 15, 20):