V4R3 contains two new commands that make it easier to move files between
DB2/400 and other databases. You can use the Copy To Import File (CPYTOIMPF) command to convert data to a different format before it is sent to another system. Also, you can use the Copy From Import File (CPYFRMIMPF) command to format data that has been received from another system. These commands translate files between your AS/400s character set and character sets found on other systems. They can also convert between fixed-format and delimited data.
Both of these commands are part of the base operating system on V4R3 and are provided at no additional cost. PTFs make these commands available for V4R2 and V4R1 systems with some restrictions. (See the sidebar, Import File PTFs for V4R1, V4R2, and V4R3.)
Packing a Crate for Shipment
Import files can be either DB2/400 database files or AS/400 Integrated File System (AS/400 IFS) stream files. The data in the import file is typically an ASCII file with record and field delimiters. The record delimiters are usually a combination of carriage return or line feed characters, and the field delimiters are usually commas or tabs. Character data may also be surrounded by double quotes.
The CPYTOIMPF command is used to move data from your AS/400 to another system. The data can be copied to another database file or to a stream file. CPYTOIMPF is especially helpful in data warehousing environments.
As the data is copied, translation is performed, and the data is formatted. You can specify whether the file is fixed-format or delimited. For delimited files, you can also specify what character will be used to delimit records, strings, and fields. At the end of each record, the record delimiter will be inserted, the string delimiter will surround each string, and all fields will be separated by the field delimiter. Strings are the character, date, time, and time stamp fields contained in the file being copied.
Because the format of the data being converted is retrieved from the files external description, the input file for the CPYTOIMPF command must be an externally described, single-format file created by using DDS or SQL. You may also use source files, but the
date and sequence numbers are not included in the output file. The output can be either a native AS/400 file or a stream file. Any overrides, in effect, will be used when the data is copied.
Unpacking the Crate
Use the CPYFRMIMPF command to copy data from another systems format to a DB2/400 database file. The input file must reside on your AS/400 and can be a stream file, a source file, or a database file that contains one field. The CPYFRMIMPF command can determine the format of the input data in two ways. For delimited files, you can specify what characters are used to separate records, strings, and fields. Either two adjacent field delimiters, two adjacent string delimiters, a field delimiter followed by a record delimiter, or a field of all blanks indicates a null field value. If the import file data is fixed-format and does not contain any delimiters, you will have to create a field definition file. This file defines the layout and format of the file being imported. You can specify where columns start and end as well as the position of null value indicators for columns.
You can use field definition files to describe the format of files that contain fixed- format data. Lines that begin with a hyphen (-) are comments. The end of the field definition file is indicated with the special value *END. The fields in the import file are described in free-format columns of text separated by one or more blanks. The first column is the name of the field in the output file. The second and third columns are the starting and ending positions for the field. The last column is the position of the null value indicator. If the field does not have a null value indicator, specify a 0. If a null field indicator is included for a field, the indicator value in the import file must be a Y for null fields or an N for fields that are not null. Figure 1 illustrates a field definition file.
The To Coded Character Set ID (TOCCSID) keyword on the CPYTOIMPF command and the From Coded Character Set ID (FROMCCSID) keyword on the CPYFRMIMPF command determine the character conversion that these commands perform. (The Coded Character Set ID is a number that represents the set of characters used for a files data. For example, the CCSID for USA/Canada EBCDIC English is 00037, and the CCSID for 7-bit ASCII would be 00367. A list of character set IDs can be found in AS/400 International Application Development V4R2, Appendix F.)
Shipping and Receiving
After you have your data converted, you will want to move it to or from another systems database. There are many ways to do this. I prefer to use FTP or email because they are the most widely available and flexible methods of transmission. Within the bounds of your network, you may also use a file transfer utility or shared folders to access converted data on your AS/400.
You can use the Send Distribution (SNDDST) command to send an import file as an attachment to an email message. This is a three-step process, as shown in Figure 2. First, I use the CPYTOIMPF command to convert the data and copy it to a shared folder file. Shared folders are located in the QDLS directory. The CPYTOIMPF command in Figure 2 builds a comma-delimited file that can be used in Excel or Lotus 1-2-3. Next, I set the subject for email by using the Change Document Description (CHGDOCD) command. Finally, I use the SNDDST command to send the file attached to an email. These steps are necessary so that a subject can be specified and the file being sent has a meaningful name.
The Copy To Stream File (CPYTOSTMF) and Copy To PC Document (CPYTOPCD) commands can also translate and copy AS/400 database files. However, they are not as flexible as the new import file commands.
First, neither of these commands takes advantage of multiple processors and parallel processing. However, one of the main features of the import file commands is their ability to use parallel tasks to copy data. For this reason, the import file commands are collectively referred to as the Parallel Data Loader. To take advantage of parallel processing, you must have the Symmetric Multiprocessing (SMP) licensed product
installed on your system. If SMP is installed on your system, you can use the Change Query Attributes (CHGQRYA) command to set the number of tasks that will be used to perform the copy. For the best performance, set the number of tasks to one greater than the number of CPUs on your system. For example, if your system has two CPUs, the command would be entered as CHGQRYA DEGREE(*NBRTASKS 3). You may want to experiment with different values. Specifying too few tasks will prevent the copy from using all of your systems CPUs. Specifying too many tasks may overcommit memory resources and also requires extra overhead to manage the tasks.
Second, CPYTOSTMF can convert data and add record separators. However, it cannot distinguish delimited fields or take advantage of SMP.
CPYTOPCD is restricted to copying data from a DB2/400 database file to a shared folder. Conversion is done from EBCDIC to ASCII when the data is copied. Both of these commands are adequate for fixed-format files, but, for delimited files, you will want to use the Parallel Data Loader commands.
Verify the Shipment Against the Manifest
After using the Parallel Data Loader commands to convert the format of your data, it is a good idea to verify that the values sent match the values received. This is especially true the first time an import file is used or whenever the format of the data has changed. The CPYTOIMPF checks only to see that the data being copied is not truncated as it is converted and placed into the import file. The CPYFRMIMPF command performs even less validation. Both numeric and character values can be truncated. In some cases, a diagnostic message will be sent but not for numeric truncation or with the PTF version supplied for V4R2. In addition, if more fields are included in the import file than are contained in the output file, they will be dropped.
Air Freight Replaces Rail
AS/400 users now have commands that provide a fast and flexible way to convert data that will be moved between AS/400s and other platforms. Before IBM included this support, a third-party product or custom programming was required. The import file commands come in handy, especially when you need to move delimited files to or from your AS/400.
AS/400 International Application Development V4R2 (SC41-5603-01, CD-ROM QB3AQ501)
OS/400 CL Reference V4R3 (SC41-5722-02, CD-ROM QB3AUP02) OS/400 TCP/IP Configuration and Reference V4R3 (SC41-5420-02, CD-ROM QB3ANL02)
Import File PTFs for V4R1, V4R2, and V4R3
The import file commands were not available when V4R1 and V4R2 were released. IBM has made both commands available to V4R2 users through PTF SF46911. However, on V4R1, only the Copy From Import File (CPYFRMIMPF) command is available. The PTF is SF47138. There are prerequisite PTFs for these commands, which are listed in the PTF cover letters. The PTF versions do have a few rough edges. For example, there are some inconsistencies between the help text and the command, and a few keyword values are not supported. At the time this article was written, IBM had also issued PTFs to correct problems in the Copy To Import File (CPYTOIMPF) command. These PTFs are SF52611 on V4R3 and SF52610 on V4R2. Because CPYTOIMPF is not available for V4R1, there is no fix for this release.
-* Sample Field Definition file describing a fixed *
-* format import file containing three fields. The first *
-* field also has a null indicator flag of 'Y' or 'N' *
-* The file is terminated with the special value *END. *
-* Column one is the output file field name. *
-* Column two is the import files field starting positon. *
-* Column three is the field ending position. *
-* Column four is the position of the null indicator. *
Field1 1 10 11
Field2 12 13 0
Filed3 14 16 0
Figure 1: A field definition file defines the fields of an import file.
CPYTOIMPF FROMFILE(Lib/File Mbr) TOSTMF('/QDLS/Folder/File.Ext') +
MBROPT(*REPLACE) RCDDLM(*CRLF) STRDLM('"') FLDDLM(', ')
CHGDOCD DOC(File.Ext) FLR(Folder) DOCD('Message subject')
SNDDST TYPE(*DOC) TOINTNET((user@domain)) +
DSTD('Required distribution description') +
MSG('Message text') DOC(File.Ext) FLR(Folder)
Figure 2: Preparing and emailing an import file for PC-based spreadsheet programs are easy.