Question

地狱的家伙刚跳进python，我很难搞清楚这个

我有2个查询。。 query1 和 query2 现在我该怎么说呢 row = cursor.fetchone() ，我指的是 query1 而不是 query2

cursor = conn.cursor()
query1  = cursor.execute("select * FROM spam")
query2  = cursor.execute("select * FROM eggs")
row = cursor.fetchone ()

谢谢你们

Answer 1

执行第二个查询后，第一个查询的结果就消失了。（execute的返回值没有用。）同时处理两个查询的正确方法是使用两个游标：

cursor1 = conn.cursor()
cursor2 = conn.cursor()
cursor1.execute("select * FROM spam")
cursor2.execute("select * FROM eggs")
cursor1.fetchone() #first result from query 1
cursor2.fetchone() #first result from query 2

Answer 2

没有。来自cursor.execute的返回值毫无意义。每PEP 249：

.execute(operation[,parameters]) 

        Prepare and execute a database operation (query or
        command)...

        [...]

        Return values are not defined.

Answer 3

你无法按照自己的方式去做。做这样的事情：

cursor = conn.cursor()
cursor.execute("select * FROM spam")
results1 = cursor.fetchall()
cursor.execute("select * FROM eggs")

if results1 is not None and len(results1) > 0:
    print "First row from query1: ", results1[0]

row = cursor.fetchone()
if row is not None:
    print "First row from query2: ", row

我可以在一个变量中存储一个cursor.fetchone（）

3 个答案: