Host Variables

The host variables are the data elements that are specified in the COBOL program. Host variables either take data from a table or add the data to a table. These variables are used to store and retrieve values from databases.

In the File, Local Storage, Linkage, or Working-Storage sections of your COBOL program, you can assign host variables with any level number between 1 and 48. VARCHAR data elements have level 49 designated for them.

Host variables cannot be group items, however, they can be grouped in the host structure. They cannot be altered in meaning or name.

If you utilize a host variable in an embedded SQL query, you must use a colon to provide the prefix of the data item name (:). To help the compiler distinguish between host variables and columns/tables with the same name, use the colon (:).

There are two ways to use host variables:

• Input Host variables: Defining the data that will be sent from the COBOL application to the database using input host variables.
• Output Host Variables: Used to store information that the database returns to the COBOL program.

Syntax:

  EXEC SQL  

  INCLUDE table-name  

  END-EXEC.   

  EXEC SQL BEGIN DECLARE SECTION  

  END-EXEC.  

  Data    

  EXEC SQL END DECLARE SECTION  

  END-EXEC.  

Programs in COBOL communicate with the DB2 Database. Data Base2 is DB2, and it was created by IBM. The database is a relational one. The relational information is kept in the TABLE format, which consists of multiples of rows and attributes (Columns).

DB2 is generally used for storing sizable amounts of Mainframe application data. It is comparable to SQL but has several enhanced features.

The following terms are part of the COBOL vocabulary for the Database Interface:

• Embedded SQL
• DB2 Application Programming
• Host Variables
• SQLCA
• SQL Queries
• Cursors