建表格式: create table if not exists 表名 (列名 类型,....) 注: 如需生成默认增加的id: id integer primary key auto increment
删除表
DROP TABLE IF EXISTS 't_student';
- 创建表
CREATE TABLE IF NOT EXISTS 't_student' (
'id' INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
'name' TEXT,
'age' INTEGER
);
- 插入数据
INSERT INTO t_student (name, age) VALUES ('name', age);
- 更新数据
UPDATE t_student SET age = 30 WHERE name = 'why';
UPDATE t_student SET name = 'zs' WHERE age > 20;
- 删除数据
DELETE FROM t_student WHERE name = 'zs’;
- 基本查询
SELECT * FROM t_student;2.
- 查询特殊的字段
SELECT name, age FROM t_student;3.
- 通过条件来查询语句
SELECT name, age FROM t_student WHERE age <= 25;4.
-
通过条件查询
- 模糊查询
SELECT name, age FROM t_student WHERE name LIKE '%l%';5.
- 多个条件的查询
SELECT name, age FROM t_student WHERE name LIKE '%l%' AND age >=25;
SELECT name, age FROM t_student WHERE name LIKE '%l%' OR age >=25;
- 计算个数
SELECT count(*) FROM t_student;SELECT count(name) FROM t_student;SELECT count(age) FROM t_student;
数据的排序
升序 ASC 默认情况
SELECT * FROM t_student ORDER BY age;
- 降序 DESC
SELECT * FROM t_student ORDER BY age DESC;
- 例如以年龄的升序排序
如果年龄相同 以名字的降序排序
SELECT * FROM t_student ORDER BY age, name DESC;
- 起别名
- 给表起别名
SELECT [s.name](http://s.name "Page 2")
, s.age FROM t_student AS s;
- 给数据库字段起别名
SELECT name AS myName, age AS myAge FROM t_student;
- 查询
SELECT name, age FROM t_student LIMIT 4, 2;2>
- 该语句的意思是:跳过0条数据 查询前五条数据
SELECT name, age FROM t_student LIMIT 5;
