The Field Synonym: ALIAS

In this section:

Implementing a Field Synonym

You can assign every field an alternative name, or alias. A field alias may be its original name as defined to its native data source, any name you choose, or, in special cases, a predefined value. The way in which you assign the alias is determined by the type of data source and, in special cases, the role the field plays in the data source. After it has been assigned, you can use this alias in requests as a synonym for the regular field name. Assign this alternative name using the ALIAS attribute.

Example: Using a Field Synonym

In the EMPLOYEE data source, the name CURR_SAL is assigned to a field using the FIELDNAME attribute, and the alternative name CSAL is assigned to the same field using the ALIAS attribute:

FIELDNAME = CURR_SAL, ALIAS = CSAL, USAGE = D12.2M,  $

Both names are equally valid within a request. The following TABLE requests illustrate that they are functionally identical, refer to the same field, and produce the same result:

TABLE FILE EMPLOYEE
PRINT CURR_SAL BY EMP_ID
END
 
TABLE FILE EMPLOYEE
PRINT CSAL BY EMP_ID
END

Note: In extract files (HOLD, PCHOLD), the field name is used to identify fields, not the ALIAS.

Implementing a Field Synonym

The value you assign to ALIAS must conform to the same naming conventions to which the FIELDNAME attribute is subject, unless stated otherwise. Assign a value to ALIAS in the following way for the following types of data sources:

Relational data sources. ALIAS describes the field original column name as defined in the relational table.
Sequential data sources. ALIAS describes a synonym, or alternative name, that you can use in a request to identify the field. You can assign any name as the alias. Many users choose a shorter version of the primary name of the field. For example, if the field name is LAST_NAME, the alias might be LN. The ALIAS attribute is required in the Master File, but it can have the value blank.
Note that ALIAS is used in a different way for sequenced repeating fields, where its value is ORDER, as well as for RECTYPE and MAPVALUE fields when the data source includes multiple record types. For more information, see Describing a Sequential, VSAM, or ISAM Data Source.
FOCUS data sources. ALIAS describes a synonym, or alternative name, that you can use in a request to identify the field. You can assign any name as the alias. Many users choose a shorter version of the primary name of the field. For example, if the field name is LAST_NAME, the alias might be LN. The ALIAS attribute is required in the Master File, but it can have the value blank. For more information, see Describing a FOCUS Data Source. Aliases can be changed without rebuilding the data source. If an alias is referred to in other data sources, similar changes may be needed in those Master Files.