1 INVOKE Specifies the name of the database to be accessed in a program or by RDO. You must issue an INVOKE DATABASE statement before you can use any other statement to reference data in that database. Using INVOKE is equivalent to declaring an external subroutine; it declares the database to the program. Example: RDO> INVOKE DATABASE FILENAME 'DISK2:[DEPT4]PERSONNEL' 2 Format (B)0INVOKE DATABASE qwqqqqqqqqqqqqqqqqqqqqq>qqqqqqqqqqqqqqqqqqqqqqqqwqqk tqqqqqqqqqqqq>qqqqqqqqqqqqqqwq> db-handle q> = j x mq> db-handle-scope-optionsqj x lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqwqqwqq> PATHNAME qqq> path-name qqwqk mqq> COMPILETIME qqqj mqq> FILENAME qqq> file-spec qqj x lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqwqqqk mqq> RUNTIME FILENAME qqqqwqqqq> file-spec qqqqqqqqwqqqj x mqqqq> host-variable qqqqj x lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqwqqk mqq> DBKEY SCOPE IS qqqwqqq> COMMIT qqqqqqwqqqqqqqj x mqqq> FINISH qqqqqqj x lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqwqqqqqqk mqq> REQUEST_HANDLE SCOPE IS qwq> DEFAULT qqwqj x mq> FINISH qqqj x lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqwqqq> mqq> PRESTARTED TRANSACTIONS ARE qqwqq> ON qqqqqqqqqu mqq> OFF qqqqqqqqqj 3 db-handle A host language variable that you associate with the name of the database. Use database handles when you are accessing more than one database at a time. Do not declare a host language variable explicitly for the database handle. The Oracle Rdb preprocessors declare the variable for you. You can make a handle local to the module in which it is declared (LOCAL), or global to all modules that declare the database (GLOBAL, EXTERNAL). The default is GLOBAL. 3 path-name A full or relative data dictionary path name specifying the source of the database definitions. 3 file-spec A full or partial OpenVMS file specification specifying the source of the database definitions. 3 host-variable A valid host language variable that equates to a database file specification. 3 COMPILETIME The source of the database definitions when the program is compiled. This can be either a data dictionary path name or an OpenVMS file specification. If you specify only the COMPILETIME identifier and omit the RUNTIME identifier, Oracle Rdb uses the COMPILETIME identifier for both compiling and running the program. 3 RUNTIME The source of the database definitions when the program is run. This can be either an OpenVMS file specification or a host language variable. If you do not specify this parameter, Oracle Rdb uses the COMPILETIME identifier for both compiling and running the program. 3 DBKEY_SCOPE_COMMIT The DBKEY SCOPE clause controls when the database key (dbkey) of an erased record may be reused by Oracle Rdb. When the DBKEY SCOPE is COMMIT, Oracle Rdb cannot reuse the dbkey of an erased record to store another record until the transaction that erased the original record completes (by entering COMMIT). The DBKEY SCOPE COMMIT clause specifies that the dbkey of each record used is guaranteed to remain consistent only during each transaction. 3 DBKEY_SCOPE_FINISH With the DBKEY SCOPE IS FINISH clause, Oracle Rdb cannot reuse the dbkey (to store another record) until the user who erased the original record detaches from the database (by using the FINISH statement). Further, the DBKEY SCOPE FINISH clause specifies that the dbkey of each record used is guaranteed not to change until this user detaches from the database(usually, with FINISH). 3 REQUEST_HANDLE_SCOPE_DEFAULT The REQUEST_HANDLE SCOPE clause is only used by RDBPRE and RDML programs, not with RDO or RDB$INTERPRET. In a RDBPRE program where an RDO request occurs within a higher level language loop, the REQUEST_HANDLE SCOPE clause determines whether system or user request handles are set to zero in the RDO FINISH statement within the loop. The default is DEFAULT, where the values of the request handles are not set to zero when the RDO FINISH statement executes. 3 REQUEST_HANDLE_SCOPE_FINISH The REQUEST_HANDLE SCOPE clause is only used by RDBPRE and RDML programs, not with RDO or RDB$INTERPRET. In a program where an RDO request occurs within a higher level language loop, the REQUEST_HANDLE SCOPE clause determines whether system or user request handles are set to zero in the RDO FINISH statement within the loop. With the REQUEST_HANDLE SCOPE is FINISH clause, the values of the request handles are set to zero after the RDO statement FINISH executes. 3 PRESTARTED_TRANSACTIONS_ARE_ON Explicitly enables prestarted transactions. For most applications, Rdb recommends that you enable prestarted transactions. The default is PRESTARTED TRANSACTIONS ARE ON. If you use the PRESTARTED TRANSACTIONS ARE ON clause or do not specify the PRESTARTED TRANSACTIONS clause, the COMMIT or ROLLBACK statement for the previous read/write transaction automatically reserves the TSN for the next transaction and reduces I/O. 3 PRESTARTED_TRANSACTIONS_ARE_OFF Disables prestarted transactions. Use the PRESTARTED TRANSACTIONS ARE OFF clause only if your application uses a server process that is attached to the database for long periods of time and causes the snapshot file to grow excessively. If you use the PRESTARTED TRANSACTIONS ARE OFF clause, Oracle Rdb uses additional I/0 because each START TRANSACTION statement must reserve a transaction sequence number (TSN). 2 More You must have the Oracle Rdb READ privilege for a database to invoke it using the INVOKE DATABASE statement. 2 Examples Example 1 The following example invokes a database in RDO: RDO> INVOKE DATABASE PATHNAME 'DISK1:[DICTIONARY]CORP.MIS.PERSONNEL' This example uses the data dictionary definitions in DISK1:[DICTIONARY]CORP.MIS.PERSONNEL to invoke the PERSONNEL database in RDO. Example 2 The INVOKE DATABASE statement must be part of every program: &RDB& INVOKE DATABASE FILENAME 'DISK2:[DEPT3]PERSONNEL' This statement declares the database defined by the file specification DISK2:[DEPT3]PERSONNEL. The preprocessor then uses this definition when compiling the program, and Oracle Rdb uses the database file DISK2:[DEPT3]PERSONNEL.RDB when the program runs. Example 3 The following BASIC example invokes a database using an EXTERNAL database handle: &RDB& INVOKE DATABASE EXTERNAL &RDB& PERSONNEL = PATHNAME 'DISK1:[DICTIONARY]CORP.MIS.PERSONNEL' This example shows a global declaration. Other modules in the program can refer to the database using the handle PERSONNEL; they must use the same database handle for the same database. The program does not declare the variable. o GLOBAL and EXTERNAL are synonymous. These make the database handle global to all modules that declare the database. Oracle Rdb creates a PSECT containing one longword using the name supplied by the user with the overlay attribute. o The default database scope is GLOBAL. o The preprocessor generates declarations for all database handles. Example 4 The following COBOL example uses the COMPILETIME and RUNTIME options: &RDB& INVOKE DATABASE LOCAL PERSONNEL = &RDB& COMPILETIME PATHNAME &RDB& 'DISK1:[DICTIONARY]ACCT.PERSONNEL' &RDB& RUNTIME FILENAME &RDB& 'USERDISK3:[DEPT3]PERSONNEL' This example declares the database using two different sources: o At compile time, the preprocessor uses the database definitions in the data dictionary. o At run time, Oracle Rdb uses the definition in file USERDISK3:[DEPT3]PERSONNEL.RDB.