Question

我正在试验Teradata python模块教程here

我正在执行一个查询，我想多次迭代结果集。问题是如果我迭代结果集一次，我不能再做了。看起来结果集已用完，无法再进一步计算。

有关详细信息，请参阅以下代码，并建议如何保留结果集。

import teradata

class DB():
    def __init__(self):
        udaExec = teradata.UdaExec (appName="HelloWorld", version="1.0",logConsole=False)
        session = udaExec.connect(method="odbc", system="tddemo",username="dbc", password="dbc")
        self.session = session

    def fun1(self):
        rows = self.session.execute("SELECT  databasename, ownername  FROM DBC.DATABASES  where DatabaseName='financial'")
        return rows

db = DB()
rows = db.fun1()

# This loop prints accurate result like
#Row 1: [financial, Samples]
for row in rows:
    print(row)

# This loop does not print anything
for row in rows:
    print(row)  

# This line also gets printed
print("The End")

Answer 1

生成器只能迭代一次，使用list或tuple进行转换，然后您可以多次迭代它：

rows = tuple(db.func1())

for row in rows:
    # do something

for row in rows: # would work
    # do something else

Teradata Python模块游标结果集在一次迭代后耗尽

1 个答案: