原生sql查询数据库

在setting中配置pymysql

1、增加

import pymysql
conn = pymysql.connect(
    host="localhost",
    port=3306,
    database="2008a",
    user="root",
    password="123456",
    charset="utf8",
)
cursor = conn.cursor()
# 拼接语句
sql = "insert into student3(id,name,age)VALUES (0,%s,%s)"
# 执行
data=("王五",18)
try:
    cursor.execute(sql, data)
    conn.commit()
except Exception as e:
    print("报错啦：",str(e))
    conn.rollback()  # 回滚
# 对数据库做写操作一定要记得提交assword

cursor.close()
conn.close()

2、增加多条数据

import pymysql
conn = pymysql.connect(
        host="localhost",
        port=3306,
        database="2008a",
        user="root",
        password="123456",
        charset="utf8",
)
cursor = conn.cursor()
# 创建班级的sql语句
sql="insert into student3(id,name,age)VALUES (0,%s,%s)"
data=[("alex1",16),("污Sir1",17),("xiaoyima1",18)]
try:
    cursor.executemany(sql, data)  # 内部实现for循环，批量执行插入语句
    conn.commit()  # 提交一次
except Exception as e:
    print("错啦！")
    conn.rollback()
cursor.close()
conn.close()

3、删除

import pymysql
conn = pymysql.connect(
            host="localhost",
            port=3306,
            database="2008a",
            user="root",
            password="123456",
            charset="utf8",
)
cursor = conn.cursor()
# sql = "delete from info WHERE name=%s"
sql = "delete from student3 WHERE id=%s"
cursor.execute(sql,2)
conn.commit()
cursor.close()
conn.close()

4、修改数据

import pymysql
conn = pymysql.connect(
        host="localhost",
        port=3306,
        database="2008a",
        user="root",
        password="123456",
        charset="utf8",
)
cursor = conn.cursor()
sql = "update student3 set age=%s where name=%s"
cursor.execute(sql,[123, "张三"])
conn.commit()
cursor.close()
conn.close()

5、查询数据

import pymysql

conn = pymysql.connect(
        host="localhost",
        port=3306,
        database="2008a",
        user="root",
        password="123456",
        charset="utf8",
)

cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)  # 指定返回的数据格式为字典格式

sql = "select * from student3"

cursor.execute(sql)  # 返回的不是具体的数据而是受影响的行数
# ret = cursor.fetchall()  # 返回所有的数据
ret = cursor.fetchone()  # 返回第一条的数据
print(ret)
# ret = cursor.fetchone()  # 接着上一条返回一条数据
# print(ret)

# ret = cursor.fetchmany(3)  # 查询具体多少条数据，这里查询前三条数据
# print(ret)
# # cursor.scroll(0, mode="absolute")  # 绝对移动，写多少就是移到多少，这里从第1条数据开始查
# cursor.scroll(-1, mode="relative")   #相对移动，这里-1表示光标往前移动数据到第2条数据，从第3条数据开始查
# ret = cursor.fetchall()
# print(ret)
cursor.close()
conn.close()