SQLite Select 语句学习笔记
SELECT 语句的基本语法
sqlCopy CodeSELECT column1, column2, ...
FROM table_name;
基本用法
查询所有列
sqlCopy CodeSELECT * FROM table_name;
查询指定列
sqlCopy CodeSELECT column1, column2 FROM table_name;
搜索条件
sqlCopy CodeSELECT * FROM table_name WHERE condition;
排序
sqlCopy CodeSELECT * FROM table_name ORDER BY column_name [ASC|DESC];
实例演示
创建表格
sqlCopy CodeCREATE TABLE students (
id INTEGER PRIMARY KEY,
name TEXT NOT NULL,
age INTEGER,
score REAL
);
插入数据
sqlCopy CodeINSERT INTO students VALUES (1, 'Tom', 18, 89.5);
INSERT INTO students VALUES (2, 'Lucy', 20, 92.0);
INSERT INTO students VALUES (3, 'Mike', 19, 85.0);
查询所有信息
sqlCopy CodeSELECT * FROM students;
输出结果:
Copy Codeid | name | age | score
---|------|-----|-------
1 | Tom | 18 | 89.5
2 | Lucy | 20 | 92.0
3 | Mike | 19 | 85.0
查询姓名和成绩
sqlCopy CodeSELECT name, score FROM students;
输出结果:
Copy Codename | score
-----|------
Tom | 89.5
Lucy | 92.0
Mike | 85.0
查询年龄大于 18 的学生信息
sqlCopy CodeSELECT * FROM students WHERE age > 18;
输出结果:
Copy Codeid | name | age | score
---|------|-----|-------
2 | Lucy | 20 | 92.0
3 | Mike | 19 | 85.0
按成绩从高到低排序
sqlCopy CodeSELECT * FROM students ORDER BY score DESC;
输出结果:
Copy Codeid | name | age | score
---|------|-----|-------
2 | Lucy | 20 | 92.0
1 | Tom | 18 | 89.5
3 | Mike | 19 | 85.0
结论
本文介绍了 SQLite Select 语句的基本语法和用法,并给出了实例演示。希望可以帮助初学者更好地理解和掌握 SQLite 数据库的 SELECT 语句。