Null values for Oracle SQL Python

Question

I have a clob datapoint that I must use .read() to add it to a list, however, sometimes this column is null, so I need a check first before using the .read() property.

I've isolated the portion that is relevant. If I just print data, the null fields print as none. Is not null seems to be the wrong code, but I'm not sure what to use.

for currentrow in data:
    if currentrow[8] is not null:
        Product = currentrow[8].read()
    else:
        Product = currentrow[8]
    data = tuple([currentrow[0], currentrow[1], currentrow[2], currentrow[3], currentrow[4], currentrow[5], currentrow[6], currentrow[7], Product])
print data

Rahul Tripathi · Accepted Answer · 2014-08-21 19:00:38Z

4

From the docs:

The sole value of types.NoneType. None is frequently used to represent the absence of a value, as when default arguments are not passed to a function.

So you may try this:

for currentrow in data:
    if currentrow[8] is not None:   <-- Change this from null to None
        Product = currentrow[8].read()
    else:
        Product = currentrow[8]
    data = tuple([currentrow[0], currentrow[1], currentrow[2], currentrow[3], currentrow[4], currentrow[5], currentrow[6], currentrow[7], Product])
print data

answered Aug 21, 2014 at 19:00

Rahul Tripathi

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Martijn Pieters · Accepted Answer · 2014-08-21 19:05:12Z

3

Python uses the None singleton value as a null; NULLs from the database are translated to that object:

if currentrow[8] is not None:

You could collapse that line into just two:

for currentrow in data:
    product = currentrow[8] and currentrow[8].read()
    data = currentrow[:8] + (product,)

as Python's and operator short-circuits and None is false in a boolean context. Unless you set a row factory, cx_Oracle cursors produce tuples for each row, which you can slice to select just the first 8 elements, then append the 9th to create a new tuple from the two.

edited Aug 21, 2014 at 19:05

answered Aug 21, 2014 at 18:59

Martijn Pieters

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