SAS Companion for UNIX Environments

Accessing SAS Files from Previous Releases

Each new version of the SAS System provides new features for processing data sets. For example, Version 7 introduces integrity constraints. The only way to take advantage of these new features with existing data is to convert data sets that were created with previous versions of the SAS System into Version 7 data sets. Converting Data Libraries describes various methods to convert data libraries between versions of the SAS System.

Each version of the SAS System provides compatability engines that enable you to read and write data sets and process catalogs created with previous releases when you do not want to convert the data library. For example, if you have a data set created with any release from Release 6.09 through Release 6.12, you can read from and write to that data set using the V6 engine. To process catalogs that were created with Releases 6.09 through Release 6.12, you can use the V6 engine. However, you will not be able to take advantage of any of the new data set features such as integrity constraints unless you convert the libraries that contain these catalogs and data sets.

If you omit the engine name when you assign a libref to a directory that contains data sets that were created with an previous release, then SAS will determine the engine to use for reading the data set as described in Omitting Engine Names From the LIBNAME Statement. However, output will always default to the new format.

You must convert your Release 6.03 and Release 6.07 catalogs to Version 7 format before you can use them in a Version 7 application. See Moving and Accessing SAS Files across Operating Environments for information on converting Release 6.03 and 6.07 catalogs to Version 7.

If you are using an older release and you want to access a data set created with a newer release, convert the data set before proceeding. For example, if you are using Release 6.07 and you want to access a Version 7 data set, you must convert that data set. See Moving and Accessing SAS Files across Operating Environments for information.

To use a newer catalog in an older release, you must convert the catalog first. However, this practice is not recommended because catalog entries may not be backward compatible, so older releases may not function with converted catalogs from newer releases.

Converting Data Libraries

In general, it will be more efficient to convert older data libraries to the new V7 format unless you plan to contine both reading from and writing to the data sets in these libraries with previous releases of SAS. The method you choose to convert data libraries depends on how the libraries were created and whether you have to convert data sets only or also have to convert catalogs.

Use the CPORT and CIMPORT procedures to convert data libraries created in one release to data libraries created in a different release. These procedures must be used
- if the data libraries contain SAS catalogs
- to transport Version 5 or Version 6 data libraries from other machines.
The following example shows two programs: the first one creates an external file from a Release 6.03 catalog and must be run using Release 6.03 of the SAS System. The second program converts the external file to a Version 7 catalog and must be run using Version 7 of the SAS System.
```
 /*  Release  6.03 SAS program */ filename sascat '/users/myid/mydir/mycat.dat'; libname oldlib '/users/myid/olddir';  proc cport c=oldlib.catalog file=sascat; run;  /*  Version 7 SAS program */ filename sascat '/users/myid/mydir/mycat.dat'; libname mylib '/users/myid/mydir';  proc cimport c=mylib.catalog infile=sascat; run;
```
Refer to Moving and Accessing SAS Files across Operating Environments for more information about the CPORT and CIMPORT procedures.
Use a Version 6 compatibility engine and the COPY procedures to convert SAS data sets created on the same host.
In the following example, the V6 engine reads all the SAS data sets in a Release 6.09 SAS data library and then writes them to a Version 7 SAS data library:
```
 libname old v6 '/users/myid/trans91'; libname new v7 '/users/myid/trans93';  proc copy in=old out=new memtype=data; run;
```
Use a Version 6 compatibility engine and a DATA step to convert SAS data sets that were created on the same host.
In this example, a Release 6.09 data set is created using Version 7 of the SAS System:
```
libname old v6 '/users/myid/trans91'; libname new v7 '/users/myid/trans93';  data old.data;    set new.v6data; run;
```
The OLD.DATA data set could then be processed with Release 6.09 of the SAS System.

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