将查询结果分配给变量

Question

我有以下查询cur.execute("SELECT COUNT(addr) FROM list_table WHERE addr = '192.168.1.1'")来计算相同地址(192.168.1.1)出现在list_table表上的次数.addr属于inet类型.

当我将查询分配给变量并打印其结果时,我得到None:

res = cur.execute("SELECT COUNT(addr) FROM list_table WHERE addr = '192.168.1.1'")
print res # None

得到这样的东西的正确方法是什么？

Answer 1

您可以使用以下步骤使用python检索关系数据库的数据:

    #!/usr/bin/python
    # import the desired package
    import MySQLdb

    # Open database connection
    db = MySQLdb.connect(hostaddress,user,password,db_name)

    # prepare a cursor object using cursor() method
    cursor = db.cursor()

    # execute SQL query using execute() method.
    cursor.execute("SELECT COUNT(addr) FROM list_table WHERE addr = '192.168.1.1'")

    # Fetch a single row using fetchone() method and store the result in a variable. 
    data = cursor.fetchone()

  #OR use fetchall() method to fetch multiple rows and store the result in a list variable. 
 data = cursor.fetchall()

    print data

    # disconnect from server
    db.close()

Answer 2

您必须使用fetchone()或fetchall()从游标中获取行。

看看可用的fetch方法。

就您而言，大致如下：

res = cur.execute("SELECT COUNT(addr) FROM list_table WHERE addr = '192.168.1.1'")
row = cur.fetchone()
print(row)