DDL语句

• 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
);

DML语句

• 插入语句

INSERT INTO t_student (name, age) VALUES ('why', 18);
INSERT INTO t_student (name, age) VALUES ('lmj', 25);
INSERT INTO t_student (name, age) VALUES ('lnj', 22);
INSERT INTO t_student (name, age) VALUES ('yz', 17);
INSERT INTO t_student (name, age) VALUES ('wsz', 28);

• 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’;

DQL语句

• 基本查询

SELECT * FROM t_student;

• 查询特殊的字段

SELECT name, age FROM t_student;

• 通过条件来查询语句

SELECT name, age FROM t_student WHERE age <= 25;

• 通过条件查询(模糊查询)

SELECT name, age FROM t_student WHERE name LIKE '%l%';

• 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

1> 升序 ASC(默认)
     SELECT * FROM t_student ORDER BY age;
2> 降序 
     DESCSELECT * FROM t_student ORDER BY age DESC;
3> 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

1> 给表起别名
     SELECT s.name, s.age FROM t_student AS s;
2> 给字段起别名
     SELECT name AS myName, age AS myAge FROM t_student;

• 分页查询(limit)

1> 基本分 
     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;