CONCAT (Concatenate) keyword—logical files only

You can use this field-level keyword to combine two or more fields from the physical-file record format into one field in the logical-file record format you are defining. The name of this concatenated field must appear in positions 19 through 28.

The format of the keyword is: 
CONCAT(field-1 field-2...)

Specify the physical file field names in the order in which you want them to be concatenated, and separate them by blanks.

If the same physical field is specified more than once in a record format in the logical file (that is, by using either RENAME or CONCAT), the sequence in which the fields are specified in the logical file is the sequence in which the data is moved to the physical file on an update or insert operation. Thus, the value in the last occurrence of the physical field is the value that is put in the physical record and is the value that is used for all keys built over that physical field. All previous values of the same field are ignored.

If you want to use a field defined using the CONCAT keyword or a field specified as a parameter value on the CONCAT keyword as a key field, see the Key field name topic.

Binary character fields can be concatenated only with other binary character fields. UTF-8 fields can be concatenated only with other UTF-8 fields. UCS-2 and UTF-16 fields can be concatenated only with fields of the same type or with each other.

You cannot include a field containing decimal positions other than zero in a concatenated field. You can include a field having decimal positions of zero in which case the field is treated as an integer field.

The IBM® i program assigns the length of the concatenated field as the sum of the lengths (digits and characters) of the fields included in the concatenation.

The operating system assigns the field to be fixed length or variable length based on the fields that are concatenated. The general rules are:
  • Concatenation of a variable-length field to either a fixed-length field or another variable-length field results in a variable-length field.
  • Concatenation of a fixed-length field to a fixed-length field results in a fixed-length field unless the VARLEN keyword is also specified on the same field as the CONCAT keyword.
    Note: If the result of the concatenation is a variable-length field, a field that allows the null value, a UCS-2 field, a UTF-16 field, a UTF-8 field, or a binary character field, the CONCAT field must be input only (I in position 38). If a logical file record format contains a concatenation, it cannot contain any fields that allow the null value from the physical file record format of the based-on file.
The operating system assigns the data type based on the data types of the fields that are being concatenated. The general rules are:
  • If the concatenation contains one or more hexadecimal (H) fields, the resulting data type is hexadecimal (H).
  • If the concatenation contains one or more character (A) fields, but no hexadecimal fields, the resulting data type is character (A).
  • If the concatenation contains only numeric (S, P, B) fields, the resulting data type is zoned decimal (S).
  • If the concatenation contains UTF-8 fields, the result is a UTF-8 field.
  • If the concatenation contains UCS-2 or UTF-16 field, the result is UTF-16 if there is at least one UTF-16 field in the list; otherwise, the result is UCS-2.
  • If the concatenation contains binary character fields, the result is binary character.

When concatenating numeric fields, the sign of the farthest right field in the concatenation is used as the sign of the concatenated field. The signs of the other fields are ignored; however, they are present in the concatenated field. Therefore, if a negative value appears in a field other than the last field, you must take appropriate action to delete the embedded signs (such as converting the concatenated field to packed decimal).

The maximum length of a concatenated field varies, depending on the data type of the concatenated field and the length of the fields being concatenated. If the concatenated field is zoned decimal (S), its total length cannot exceed 63 bytes. If the field is character (A) or hexadecimal (H), its total length cannot exceed 32 766 bytes. If the concatenated field is a variable length field, its total length cannot exceed 32 740 (32 739 if the field also allows the null value).

You cannot include a floating-point, date, time, or timestamp field in a concatenated field.

In join logical files, the fields to be concatenated must be from the same physical file. The first field specified on the CONCAT keyword identifies which physical file is used. The first field must, therefore, be unique among the physical files the join logical file is based on, or you must also specify the JREF keyword following the CONCAT keyword to specify which physical file to use.

Examples

The following examples show how to specify the CONCAT keyword.

Example 1

MTH, DAY, and YEAR are fields in the physical file that are concatenated into one field DATE in the logical file, as shown in the following example.

|...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
00010A          R RECORD1                   PFILE(PF1)
00020A            DATE                      CONCAT(MTH DAY YEAR)
     A

Example 2

In the following example, if the program changes DATE from 01 03 81 to 02 05 81, the value placed in the physical record does not change because the fields specified last are MTH (value 01), DAY (value 03), and YEAR (value 81). However, if MTH, DAY, and YEAR are changed to new values, the value of DATE in the physical record also changes.

|...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
00010A          R RECORD2                   PFILE(PF1)
00020A            DATE                      CONCAT(MTH DAY YEAR)
00030A            MTH
00040A            DAY
00050A            YEAR
     A

Example 3

In the following example, fields from the physical file are concatenated into more than one field in the logical file.

|...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
00010A          R RECORD3                   PFILE(PF1)
00020A            DATE                      CONCAT(MTH DAY YEAR)
00030A            CMPDAT                    CONCAT(DAY MTH YEAR)
     A

Example 4

In the following example, if the fields from PF1 are:
  • FIXED1 is a fixed length field.
  • FIXED2 is a fixed length field.
  • VARLEN1 is a variable length field.
The resulting fields are:
  • FIELD1 is a variable length field.
  • FIELD2 is a fixed length field.
  • FIELD3 is a variable length field.
|...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
00010A          R RECORD4                   PFILE(PF1)
00020A            FIELD1                    CONCAT(FIXED1 VARLEN1)
00030A            FIELD2                    CONCAT(FIXED1 FIXED2)
00040A            FIELD3                    CONCAT(FIXED1 FIXED2)
00050A                                      VARLEN
     A