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'
1 – Format
(B)0[mINVOKE [4mDATABASE[m qwqqqqqqqqqqqqqqqqqqqqq>qqqqqqqqqqqqqqqqqqqqqqqqwqqk
tqqqqqqqqqqqq>qqqqqqqqqqqqqqwq> db-handle q> = j x
mq> db-handle-scope-optionsqj x
lqqqqqqqqqqqqqqqqqqqqqqqqq<qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj
mqqwqqqqqqqqq>qqqqqqqqqwqqwqq> [4mPATHNAME[m qqq> path-name qqwqk
mqq> [4mCOMPILETIME[m qqqj mqq> [4mFILENAME[m qqq> file-spec qqj x
lqqqqqqqqqqqqqqqqqqqqqqqqqq<qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj
mqqwqqqqqqqqqqqqqqqqqqqqqqqqq>qqqqqqqqqqqqqqqqqqqqqqqqqqqqwqqqk
mqq> [4mRUNTIME[m FILENAME qqqqwqqqq> file-spec qqqqqqqqwqqqj x
mqqqq> host-variable qqqqj x
lqqqqqqqqqqqqqqqqqqqqqqqqqq<qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj
mqqwqqqqqqqqqqqqqqqqqqqqqqqqq>qqqqqqqqqqqqqqqqqqqqqqqwqqk
mqq> [4mDBKEY[m [4mSCOPE[m IS qqqwqqq> [4mCOMMIT[m qqqqqqwqqqqqqqj x
mqqq> [4mFINISH[m qqqqqqj x
lqqqqqqqqqqqqqqqqqqqqqqqqqq<qqqqqqqqqqqqqqqqqqqqqqqqqqqqj
mqqwqqqqqqqqqqqqqqqqqqqqqqqqq>qqqqqqqqqqqqqqqqqqqwqqqqqqk
mqq> [4mREQUEST_HANDLE[m [4mSCOPE[m IS qwq> [4mDEFAULT[m qqwqj x
mq> [4mFINISH[m qqqj x
lqqqqqqqqqqqqqqqqqqqqqqqqqq<qqqqqqqqqqqqqqqqqqqqqqqqqqqqj
mqqwqqqqqqqqqqqqqqqqqqqqqqqqq>qqqqqqqqqqqqqqqqqqqqqqqqqqwqqq>
mqq> [4mPRESTARTED[m [4mTRANSACTIONS[m [4mARE[m qqwqq> [4mON[m qqqqqqqqqu
mqq> [4mOFF[m qqqqqqqqqj
1.1 – 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.
1.2 – path-name
A full or relative data dictionary path name specifying the
source of the database definitions.
1.3 – file-spec
A full or partial OpenVMS file specification specifying the
source of the database definitions.
1.4 – host-variable
A valid host language variable that equates to a database file
specification.
1.5 – 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.
1.6 – 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.
1.7 – 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.
1.8 – 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).
1.9 – REQUEST_HANDLE_SCOPE_DEFAULT
The REQUEST_HANDLE SCOPE clause is only used by RDBPRE and RDML
programs, not with RDO or RDB$INTERPRET. In a RDBPRE program
where an RDO request occurs within a higher level language loop,
the REQUEST_HANDLE SCOPE clause determines whether system or
user request handles are set to zero in the RDO FINISH statement
within the loop.
The default is DEFAULT, where the values of the request handles
are not set to zero when the RDO FINISH statement executes.
1.10 – REQUEST_HANDLE_SCOPE_FINISH
The REQUEST_HANDLE SCOPE clause is only used by RDBPRE and RDML
programs, not with RDO or RDB$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.
1.11 – 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.
1.12 – 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.
3 – 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.