OleDbDataReader not giving same results as SQL Developer

Question

The following query on my oracle db gives results that look fine when run in SQL Developer.

select * 
from guideline$ a left outer join textfragment$ t 
    on (a.TEXTFRAGMENT_CODE = t.TEXTFRAGMENT$_CODE) 
start with a.knowledge$_Code = 71122 and a.guideline$_pcode is null
connect by prior a.guideline$_Code = a.guideline$_pcode 
order SIBLINGS by a.tag_order

All rows are populated correctly. When the same exact query is ran in my program using OleDbReader.ExecuteReader() some of the rows contain a null value for a specific column when they didn't in my SQL Developer results. The data type of that column is CLOB. I can not see any pattern as to why some of the rows have a null value and some do not.

Not sure what other information would be helpful...

Does anyone have any ideas on what might be going on?

Which method do you use to read the value of the CLOB column? `GetBytes()`? — neutrino, Dec 04 '13 at 20:03
GetValue(), and then Convert.ToString()... (I didn't write this code) — ZWand19, Dec 04 '13 at 20:18

score 0 · Answer 1 · answered Dec 04 '13 at 20:24

0

Your problem may be related to the way that binary data is retrieved with OleDbDataReader.

You should use GetBytes(), and follow this article.

answered Dec 04 '13 at 20:24

neutrino

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Thanks, looks promising – ZWand19 Dec 04 '13 at 20:42
keep getting an InvalidCastException when I try and use GetBytes() or GetChars() – ZWand19 Dec 05 '13 at 16:54
Which OleDb driver are you using? – neutrino Dec 05 '13 at 22:26
11.2.0.1, I think that's what you're asking – ZWand19 Dec 06 '13 at 20:10
I mean, Microsoft? Oracle? – neutrino Dec 06 '13 at 20:44
Given that version number, I would say that it's the Oracle provider, isn't it? – neutrino Dec 06 '13 at 20:50
Yes Oracle, and yeah GetBytes, GetChars, GetString all give an InvalidCastException. Even before I try and read any data if I break in the debugger and enumerate the results only some of the rows have the data and some are null. – ZWand19 Dec 06 '13 at 21:27
Have you tried to call `GetString`only for those records with CLOB columns where `IsDBNull`returns `false`? – neutrino Dec 06 '13 at 22:22

OleDbDataReader not giving same results as SQL Developer

1 Answers1