python 简单的数据库 sqlite

'''
练习：
1,建立一个学生成绩表 Grades，学号  姓名  成绩  名次
CREATE TABLE Grades (num INTEGER PRIMARY KEY,name TEXT,grade INTEGER,rank INTEGER)
2，往表中插入10数据
INSERT IN TO Grades (num,name,grade,rank) VALUES (1,’zhangsan’,398,20)
3，查询成绩大于60分的人的名字
SELECT name,grade FROM grades WHERE grade > 60
4，查询成绩小于60分的人的个数
SELECT COUNT(*) FROM grades WHERE grade < 60
5，把成绩小于60分的人的成绩修改成60分
UPDATE grades SET grade = 60 WHERE grade < 60
6，删除全部学号小于100的人的信息
DELETE FROM grades WHERE num < 100
6，查询姓“张”的人的全部信息
SELECT * FROM grades WHERE name LIKE '张%'
7，查询全部人的成绩，按照成绩从高到低排列
SELECT grade FROM grades ORDER BY grade DESC
8，查询全部人的成绩，按照名次从小到大排列
SELECT grade FROM grades ORDER BY rank ASC
'''
import sqlite3
connect = sqlite3.connect('database01.db')
cursor = connect.cursor()
# 插入一张表，学生成绩表Grades: num, name;grade;rank
sql = "CREATE TABLE Grades(num INTEGER PRIMARY KEY,name TEXT,grade INTEGER,rank INTEGER)"
#cursor.execute(sql)
# 2 添加数据
sql = "INSERT INTO Grades(num,name,grade,rank) VALUES (10,'王昭君',600,10)"
#cursor.execute(sql)
connect.commit()

# 3 查询成绩大于60 分的人的名字
sql = 'SELECT name,grade FROM Grades WHERE grade> 60'
rs = cursor.execute(sql)
rs = list(rs)
print(rs)
connect.commit()
# 查询成绩小于400 分的人的名字
sql = 'SELECT COUNT(*) FROM Grades WHERE grade<400'
rs = cursor.execute(sql)
rs = list(rs)
print(rs)
connect.commit()
# 5 把成绩小于400的成绩改成 400
sql = 'UPDATE Grades SET grade = 400 WHERE grade<400'
cursor.execute(sql)
connect.commit()
# 6 删除学号小于5的人的信息
sql = 'DELETE FROM Grades WHERE num <5'
cursor.execute(sql)
connect.commit()
#7 查找姓 张的人的全部信息
sql = "SELECT * FROM Grades WHERE name like '张%'"
rs = cursor.execute(sql)
for x in rs:
    print(x)
connect.commit()
# 8 查询全部人的成绩，按照成绩从高到低排列
sql = 'SELECT name,grade FROM Grades ORDER BY grade DESC'
rs = cursor.execute(sql)
rs = list(rs)
print(rs)
connect.commit()

# 9 查询全部人的成绩，按照名次从小到大排列
sql = 'SELECT name,grade FROM Grades ORDER BY rank ASC'
rs = cursor.execute(sql)
rs = list(rs)

print(rs)
connect.commit()

 

1.建立新表
create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..)

2.删除表
drop table tabname

3.查询：select * from table1 where 范围

4.插入：insert into 表名(字段名1,字段名2) values(值1,值2)

5.删除：delete from table1 where 范围

6.修改：update 表名 set 修改的字段名=修改的字段值 where 范围

7.查找：select * from table1 where field1 like ’%value1%’ N%匹配以N开头     %N匹配以N结尾   %N%匹配包含N  
	[a,b]% 以a或b开头     %[a,b]以a或b结尾

	select * from table1 where field1 like 'z_'以z开头且匹配以后一个字符

	升序输出数据记录
	select * from table_name order by field asc
	降序输出数据记录
	select * from table_name order by field desc

9.总数：select count (*) from table_name;