import pymysql

#在資料庫中插入資料
def insertData(db, cursor):
    # 插入資料
    sql = """INSERT INTO student (id, name, age)VALUES
                  (1, '小明', 18),
                  (2, '小蘭', 18);"""
    try:
        # 執行sql語句
        cursor.execute(sql)
        # 提交到資料庫執行
        db.commit()

        print("successfully insert data")
    except:
        #發生錯誤時回滾
        db.rollback()

#建立mysql表
def ceartTable(cursor):
    # 建立students 資料庫, 如果存在則刪除students 資料庫
    cursor.execute("drop database if exists students")
    cursor.execute("create database students")
    #選擇 students 這個資料庫
    cursor.execute("use students")

    #sql中的內容為建立一個名為student的表
    sql = """CREATE TABLE IF NOT EXISTS `student` (
              `id` BIGINT,
              `name` VARCHAR (20),
              `age` INT DEFAULT 1
              )"""
    #如果存在student這個表則刪除
    cursor.execute("drop table if exists student")
    #建立表
    cursor.execute(sql)

    print("successfully create table")

#顯示
def readTable(cursor):
    #選擇全部
    cursor.execute("select * from student")
    #獲得返回值，返回多條記錄，若沒有結果則返回()
    results = cursor.fetchall()

    #遍歷列印
    for row in results:
        id = row[0]
        name = row[1]
        age = row[2]
        print("id =", id, " name =", name, " age =", age, '\n')

    print("successfully show table")

#查詢
def findRecord(cursor, key, value):
    #要執行的sql語句
    sql = "select * from student where " + key + "=" + value
    cursor.execute(sql)
    result = cursor.fetchall()

    print(result, "successfully find")

#刪除
def deleteRecord(db, cursor, key, value):
    #要執行的sql語句
    sql = "delete from student where " + key + "=" + value
    cursor.execute(sql)
    db.commit()

    print("successfully delete")

if __name__ == '__main__':

    # 連結mysql資料庫
    db = pymysql.connect("localhost", "root", "123456", charset="utf8")
    # 建立指標
    cursor = db.cursor()

    #建立資料庫和表
    ceartTable(cursor)

    #插入資料
    insertData(db, cursor)

    #顯示錶格
    readTable(cursor)

    #查詢
    findRecord(cursor, "name", "'小明'")

    #刪除
    deleteRecord(db, cursor, "name", "'小明'")

    #更改
    sql = "update student set age=20 where id=2"
    cursor.execute(sql)
    db.commit()

    readTable(cursor)

    # 關閉遊標連結
    cursor.close()
    # 關閉資料庫伺服器連線，釋放記憶體
    db.close()