问题
how to extract the data from mainframe into excel? Currently , I am fetching data from MS access but the requirements are for Mainframe. Thanks in advance
回答1:
First, please understand that saying "extract data from mainframe" is similar to saying "extract data from Intel." The following is not comprehensive but is intended to provide an idea of how to ask your question in a manner which can be meaningfully answered.
Please understand there is a big difference between...
- what is technically possible
- what is allowed in your shop
- what is likely to provide a robust and maintainable solution given your requirements
These are three very different things. Some of us answering questions here on Stack Overflow have life experiences that make us reticent about answering questions regarding what is technically possible absent any mention of what is allowed in your shop or what the actual business requirement is that is being solved.
Mainframes have been around for over half a century, and many shops have standard solutions to technical problems. Sometimes the solution is "don't do that, and here's what we do instead." Working against the recommendations of your technical staff, or your shop standards, is career limiting.
What operating system?
z/OS is in common use on mainframes, but there do exist shops that still run one of its ancestors like MVS/XA. The mainframe operating system traces its roots back to OS/360 first available in 1965.
z/TPF
z/Linux usually runs on top of the z/VM hypervisor.
z/VSE
In what sort of file does the data reside?
QSAM or Queued Sequential Access Method, also commonly called flat files.
VSAM or Virtual Sequential Access Method. There are several different kinds of VSAM files including KSDS (Keyed Sequential Data Set) ESDS (Entry Sequenced Data Set), RRDS (Relative Record Data Set) and Linear (conceptually similar to a memory mapped file).
a DBMS like DB2 or IMS. A DBMS typically has extract facilities to allow writing a flat file from its own internal format. DB2, for example, stores data in Linear VSAM datasets.
Unix System Services files reside in a different file system than QSAM or VSAM. This will be more familiar, as it has a directory structure where the classic z/OS file system has none.
What does the data look like?
You must know the record layout of the data you wish to retrieve.
It is common for mainframe data to include both text and binary data in a single record, for example a name and a currency amount:
Hopper Grace ar%
...which would be...
x'C8969797859940404040C799818385404040404081996C'
...in hex. This is code page 37, commonly referred to as EBCDIC.
Without knowing that the family name is confined to the first 10 bytes, the given name confined the the subsequent 10 bytes, and the currency amount is in packed decimal (also known as binary coded decimal) in the next 3 bytes, you cannot accurately transfer the data because code page conversion will destroy the currency amount which is +819.96. Converting to code page 1250, commonly in use on Microsoft Windows, you would end up with...
x'486F707065722020202047726163652020202020617225'
...where the text data is translated but the packed data is destroyed. The packed data no longer has a valid sign in the last nibble (the lower half of the last byte) and the amount itself has been changed.
Security
Is the data you wish to access covered by privacy legislation? You may have to provide some evidence that whatever protections are in place to guarantee that only authorized personnel have access to this data on the mainframe are also in place once you have transferred it off of the mainframe. Such guarantees may have to satisfy an auditor.
What you need
You need to know what operating system holds your data, you need to know what type of file holds your data (a DBMS isn't a type of file but let's let that go for now), and you need to know your record layout(s).
Typically, the easy way to retrieve data is to extract it from its existing data store (QSAM, VSAM, DBMS) into a flat file where all the data is in a text format. There are mainframe utilities to accomplish this. In extreme cases, a program can be written to accomplish this goal. Once it has been accomplished, you can transfer your data without fear of destroying packed or binary data.
You may be able to read data directly from a DBMS if that's where your data resides, but this may depend on shop standards, including security.
Modern mainframes can transfer data via FTP, FTPS, and SFTP. Which is recommended in your shop is something to ask your technical staff.
来源：https://stackoverflow.com/questions/45099285/data-extraction-from-mainframe-to-excel