将 try except 块与 python 代码结合起来

Question

我正在使用返回键和相应值的多个查询填充电子表格。脚本中使用了两个数据库连接来返回数据。

如果正在执行的 SQL 语句没有问题，则以下代码可以完美运行。如果 SQL 出现问题，程序会因错误而退出，并且我的电子表格不会被填充。

如果出现错误，我仍希望在第一列中填充键并让值返回“0”

棘手的部分是因为有两个服务器连接，一个服务器可能完美地处理 SQL，而另一个可能会抛出异常。

有没有办法可以转换这个代码块来处理它？

我是一个 Python 新手，所以深入研究错误处理有点令人生畏

# Populate the spreadsheet with data from the first set of date ranges.
row = 1
col = 0

for key, value in Queries.query_dic.iteritems():
    cur.execute(value.format(from_dateA,to_dateA))
    cur2.execute(value.format(from_dateA,to_dateA))
    rows = cur.fetchall()
    rows2 = cur2.fetchall()

    # Populate metric being queried in our horizontal headers
    worksheet[index].write(row, col, key, format)
    worksheet[index + 1].write(row, col, key, format)

    # Iterate over the data and write it out row by row.
    for return_count in rows:
        worksheet[index].write(row, col + 1, return_count[0], format2)

    for return_count in rows2:
        worksheet[index + 1].write(row, col + 1, return_count[0], format2)

    row += 1

Answer 1

经过反复试验，我找到了可行的解决方案。

# Print metric headers and counts for first date range.
row = 1
col = 0

for key, value in Queries.query_dic.iteritems():

    # Write the metrics headers
    worksheet[index].write(row, col, key, format)
    worksheet[index + 1].write(row, col, key, format)

    # Populate spreadsheet with count returned from query for Environment 1. 
    try:
        cur.execute(value.format(from_dateA,to_dateA))
        rows = cur.fetchall()
        for return_count in rows:
            worksheet[index].write(row, col + 1, return_count[0], format2)
    # Query will fail if module doesn't exist; in this case print '0'.
    except:
        worksheet[index].write(row, col + 1, '0', format2)

    # Populate spreadsheet with count returned from query for Environment 2. 
    try:
        cur2.execute(value.format(from_dateA,to_dateA))
        rows = cur2.fetchall()
        for return_count in rows:
            worksheet[index + 1].write(row, col + 1, return_count[0], format2)
    # Query will fail if module doesn't exist; in this case print '0'.
    except:
        worksheet[index + 1].write(row, col + 1, '0', format2)

    row += 1

Answer 2

要使用 try-except 你可以这样做

try:
    for key, value in Queries.query_dic.iteritems():
        cur.execute(value.format(from_dateA,to_dateA))
        cur2.execute(value.format(from_dateA,to_dateA))
        rows = cur.fetchall()
        rows2 = cur2.fetchall()

        # Populate metric being queried in our horizontal headers
        worksheet[index].write(row, col, key, format)
        worksheet[index + 1].write(row, col, key, format)

        # Iterate over the data and write it out row by row.
        for return_count in rows:
            worksheet[index].write(row, col + 1, return_count[0], format2)

        for return_count in rows2:
            worksheet[index + 1].write(row, col + 1, return_count[0], format2)

        row += 1
except:
    # Error Handling

如果你想有特定于错误的处理，你可以简单地将错误放在 except 之后

except KeyboardInterrupt:
    # Error Handling