What I want to do is parsing a flat file (attached) with fixed positions. You see there six different rows. Each row is identified with starting character. I will store the fields in the memory after parsing this file. According to the data stored in Oracle database table will modify these parsed fields and recreate the text file with modified fields?
Any approach, example code will be appreciated.
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Using the Oracle DB, you can read the flat files thanks to UTL_FILE amd creating a PL/SQL procedure you coud read each line and feed an appropriate destination table. To modify the data on the fly, on can do the tranformation in the same PL/SQL procedure or use triggers on the destination table.
Hope it helps.
Assuming the file has fixed-size fields, try this way:
create an array of integer, which represent the ordered list of each field length, then you could cycle through this array and get a substring of each row content using the array values, using them as index/length for the substring.
This way you could build an array of strings which stores the values in memory.
I will try to clarify some points:
1. The length of every row in the file is fixed (200 characters)
2. Every row has fixed-size fields. As an example the the row starting with 3 has about 60 fields with different sizes.
3. I have data in an Oracle table. This data will be used for transformation of the file. According to the data in the table some of these 159 fields will be changed. The rows starting with 4 are dependent to the row starting with 3 which is just above. The change on the rows starting with 3 will cause some changes for the rows starting with 4. (some may be removed, new ones may be created)
4. A new flat file will be created with new rows
The target is doing all the steps (parse,modify,recreate the file) in Java not PL/SQL. This file can be huge (about 1 GB). I need an approach for starting. Is using substring function the best way for parsing?
>>This file can be huge (about 1 GB). I need an approach for starting. Is using substring function the best way for parsing?
Personally i would use nio techniques for doing this. It will probably be the most efficient approach
>>As an example the the row starting with 3 has about 60 fields with different sizes.
Of course, this kind of info is crucial
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by: CEHJPosted on 2009-10-22 at 01:05:38ID: 25631686
Difficult to say exactly without knowing exactly the file spec