python连接数据库后怎样查询

import pymysql

# 打开数据库连接

db = pymysql.connect("localhost", "root", "123456", "test")

# 使用cursor()方法获取操作游标

cursor = db.cursor()

# SQL 查询语句

sql = "SELECT * FROM EMPLOYEE \

       WHERE INCOME > '%d'" % (1000)

try:

    # 执行SQL语句

    cursor.execute(sql)

    print(cursor.rownumber)

    result = cursor.fetchone()

    while result!=None:

        print(result, cursor.rownumber)

        result = cursor.fetchone()

    result = cursor.fetchone()

    print(result, cursor.rownumber)

    result = cursor.fetchone()

    print(result, cursor.rownumber)

except:

   print ("Error: unable to fetch data")

# 关闭数据库连接

db.close()

输出结果：

0

('Mac', 'Mohan', 20, 'M', 2000.0) 1

('Marry', 'Mohan', 32, 'M', 3000.0) 2

('Bob', 'Mohan', 21, 'F', 4000.0) 3

None 3

None 3

import pymysql

# 打开数据库连接

db = pymysql.connect("localhost", "root", "123456", "test")

# 使用cursor()方法获取操作游标

cursor = db.cursor()

# SQL 查询语句

sql = "SELECT * FROM EMPLOYEE \

       WHERE INCOME > '%d'" % (1000)

try:

    # 执行SQL语句

    cursor.execute(sql)

    # 获取所有记录列表

    results = cursor.fetchall()

    for row in results:

        fname = row[0]

        lname = row[1]

        age = row[2]

        sex = row[3]

        income = row[4]

        # 打印结果

        print("fname=%s,lname=%s,age=%d,sex=%s,income=%d" %

              (fname, lname, age, sex, income))

except:

   print ("Error: unable to fetch data")

# 关闭数据库连接

db.close()