What is host variable in COBOL Db2?
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.
How do you declare a host variable in SQL?
Host variables are declared using the host language specific variable declaration syntax in a declaration section. A declaration section is the portion of an embedded SQL application found near the top of an embedded SQL source code file, and is bounded by two non-executable SQL statements: BEGIN DECLARE SECTION.
How do you declare a host variable?
Procedure
- You must explicitly declare all host variables and host-variable arrays that are used in SQL statements in the WORKING-STORAGE SECTION or LINKAGE SECTION of your program’s DATA DIVISION.
- You must explicitly declare each host variable and host-variable array before using them in an SQL statement.
What is host variable in Db2?
A host variable is a data item that you declare in a program for use within an SQL statement. You can: Retrieve data into the host variable for your application program’s use. Place data into the host variable to insert into a table or to change the contents of a row.
In which section of the COBOL program should host variables be declared?
Host variables are data items defined within a COBOL program. They are used to pass values to and receive values from a database. Host variables can be defined in the File Section, Working-Storage Section, Local-Storage Section or Linkage Section of your COBOL program and have any level number between 1 and 48.
What is embedded SQL in Db2?
Embedded SQL applications connect to databases and execute embedded SQL statements. The embedded SQL statements are contained in a package that must be bound to the target database server. You can develop embedded SQL applications for the Db2® database in the following host programming languages: C, C++, and COBOL.
Can host variables be redefined?
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. For example: 01 foo1.
What is embedded SQL in DB2?
How do we use SQL statements within a host language?
Embedding SQL statements in a host language
- A DECLARE SECTION for declaring host variables.
- The main body of the application, which consists of the setup and execution of SQL statements.
- Placements of logic that either commit or rollback the changes made by the SQL statements.
What is embedded SQL in mainframe?
Embedded SQL statements are used in COBOL programs to perform standard SQL operations. Embedded SQL statements are preprocessed by the SQL processor before the application program is compiled. COBOL is known as the Host Language. COBOL-DB2 applications are those applications that include both COBOL and DB2.
What is length variables COBOL?
For single-byte character fields, the length of the declared ILE COBOL field is the number of single-byte characters in the DDS field plus 2 bytes. For DBCS-graphic data fields, the length of the declared ILE COBOL field is two times the number of DBCS-graphic characters in the DDS field plus 2 bytes.
How are host variables defined in COBOL?
What is host language?
The language that is used for database application programming is the host language for the DBMS. As mentioned earlier, a host language may be a traditional programming language, such as C or COBOL, or it may be an application-level language, such as Microsoft Access or Visual Basic, as it is for the Jet DBMS.
What is embedded SQL and dynamic SQL?
Static or Embedded SQL are SQL statements in an application that do not change at runtime and, therefore, can be hard-coded into the application. Dynamic SQL is SQL statements that are constructed at runtime; for example, the application may allow users to enter their own queries.