DB2 10.5 for Linux, UNIX, and Windows

Host variables in COBOL

Host variables are COBOL language variables that are referenced within SQL statements. Host variables allow an application to exchange data with the database manager.

After the application is precompiled, host variables are used by the compiler as any other COBOL variable. Follow the rules described in the following sections when naming, declaring, and using host variables.

Host variable names in COBOL
The SQL precompiler identifies host variables by their declared name.
Declare section for host variables in COBOL embedded SQL applications
You must use an SQL declare section must be used to identify host variable declarations. The SQL declare section alerts the precompiler to any host variables that can be referenced in subsequent SQL statements.
Example: SQL declare section template for COBOL embedded SQL applications
When you are creating an embedded SQL application in COBOL, there is a template that you can use to declare your host variables and data structures.
BINARY/COMP-4 data types in COBOL embedded SQL applications
The DB2® COBOL precompiler supports the use of BINARY, COMP, and COMP-4 data types wherever integer host variables and indicators are permitted.
SQLSTATE and SQLCODE Variables in COBOL embedded SQL application
To handle errors or debug your embedded SQL application, you should test the values of the SQLCODE or SQLSTATE variable. You can return these values as output parameters or as part of a diagnostic message string, or you can insert these values into a table to provide basic tracing support.
Declaration of numeric host variables in COBOL embedded SQL applications
Numeric host variables that you declare in your embedded COBOL application are treated as if they were declared in a COBOL program. You can use host variables to exchange data between the embedded application and the database manager.
Declaration of fixed length and variable length character host variables in COBOL embedded SQL applications
Fixed-length and variable-length character host variables that you declare in your embedded COBOL application are treated as if they were declared in a COBOL program. You can use host variables to exchange data between the embedded application and the database manager.
Declaration of fixed length and variable length graphic host variables in COBOL embedded SQL applications
Fixed-length and variable-length graphic host variables that you declare in your embedded COBOL application are treated as if they were declared in a COBOL program. You can use host variables to exchange data between the embedded application and the database manager.
Declaration of large object type host variables in COBOL embedded SQL applications
Large object (LOB) type host variables that you declare in your embedded COBOL application are treated as if they were declared in a COBOL program. You can use host variables to exchange data between the embedded application and the database manager.
Declaration of large object locator type host variables in COBOL embedded SQL applications
Large object (LOB) locator type host variables that you declare in your embedded COBOL application are treated as if they were declared in a COBOL program. You can use host variables to exchange data between the embedded application and the database manager.
Declaration of file reference type host variables in COBOL embedded SQL applications
File reference type host variables that you declare in your embedded COBOL application are treated as if they were declared in a COBOL program. You can use host variables to exchange data between the embedded application and the database manager.
Grouping data items using REDEFINES in COBOL embedded SQL applications
You can use the REDEFINES clause when declaring host variables. If you declare a member of a group data item with the REDEFINES clause, and that group data item is referred to as a whole in an SQL statement, any subordinate items containing the REDEFINES clause are not expanded.
Japanese or Traditional Chinese EUC, and UCS-2 considerations for COBOL embedded SQL applications
Any graphic data that is sent from your application running under an eucJp or eucTW code set, or connected to a UCS-2 database, is tagged with the UCS-2 code page identifier. Your application must convert a graphic-character string to UCS-2 before sending it to the database server.
Binary storage of variable values using the FOR BIT DATA clause in COBOL embedded SQL applications
You can declare certain database columns using the FOR BIT DATA clause. These columns, which generally contain characters, are used to hold binary information.
Host structure support in the declare section of COBOL embedded SQL applications
In an application program, a host structure contains a list of host variables that can be referred to by embedded SQL statements. The COBOL precompiler supports declarations of group data items in the host variable declare section.
Null-indicator variables and null or truncation indicator variable tables in COBOL embedded SQL applications
To receive null values in embedded SQL applications, you must associate null-indicator variables with declared host variables in your embedded SQL applications. A null-indicator variable is shared by both the database manager and the host application.