|Function / Data member
flag which shows whether the object is connected to the
database or not. The flag only shows that the otl_connect
object was successfully connected to the database. If the
database connection under the otl_connect object is closed,
the flag would still be set to 1. In order to check out
whether the database connection is still open or not, a
"heartbeat" database round-trip needs to be made, say, a
"SELECT <current time> FROM <dual table>", or an
actual, application related SQL statement. In other words,
in order to detect a database connection loss, a database
"heartbeat" round trip needs to be coded up in the source
static int otl_initialize
|Static (in class) function to initialize the OTL environment. It needs to be called only once at the beginning of the program before making the very first connection to the database. The threaded_mode is a parameter for specifying if the program is running in the multi-threaded mode but it does not automatically guarantee thread safety, because OTL does not set any mutex locks or critical sections. Threaded_mode = 1 means the multi-threaded mode, 0 -- the single threaded mode.|
static int otl_terminate(void);
|Static (in class) function to terminate the Oracle 8i/9i OCI environment. It needs to be called only once at the end of the program after closing the very last database connection. This function is just a wrapper around the OCITerminate() call. Usually, in multi-threaded programs, in order to be able to terminate/end the main thread of control, otl_terminate needs to be called, because it detaches the process from the OCI client side shared memory, and does something else, that is not well documented.|
|OTL/OCI8/9/10/11 only. Cancel any operation / database call, executing / active in the connect object / database session. Say, the database session is in the active state, or, in other words, has a running SQL statement in a thread. This function can be called from another thread, to cancel the execution of the SQL statement asynchronously. Right after the cancel() call returns, the first thread will raise an otl_exception with the following message: user requested cancel of current operation.|
|OTL/OCI8/9/10/11 only. This function changes Oracle user's passwords. The program needs to attach to an Oracle server, and only then this function can be called|
transaction isolation level. OTL/DB2-CLI, OTL/ODBC only.
The function allows the user to set the following levels:
READ COMMITTED, READ UNCOMMITTED, REPEATABLE READ,
SERIALIZABLE. For more detail on the transaction isolation
levels, see the regular database manuals.
OTL/ODBC and OTL/DB2-CLI define the following global constants, which can be used as substitutes for the level parameter of the function:
|Set the maximum buffer size for operations with Large Objects: varchar_long, raw_long, clob and blob. This function needs to be called in order to increase the buffer size (default size is 32767).|
|Get the maximum buffer size for operations with Large Objects: varchar_long, raw_long, clob and blob.|
|This function works in OTL 4.0/ODBC and OTL
4.0/DB2-CLI only, and it has not effect in OTL
4.0/OCIx. Sets the cursor type. Once the cursor type is set,
the setting will be propagated to all SELECT statements
opened via the otl_stream
class in the current connect object.
The following cursor types are available (for more detail, see the ODBC Programmer's Guide, or the DB2 CLI Programmer's Guide):
|This function works in OTL 4.0/ODBC only, and
has no effect in OTL 4.0/OCIx, or OTL 4.0/DB2-CLI. It sets
the timeout for the current connect object. Once the timeout
is set, the setting will be effective for all SQL statements
opened in the current connect object. The time unit for the
function is 1 second, e.g. setting 60 means the timeout of 1
In OCIx, a different technique is used to simulate timeouts: create a worker thread that will execute your SQL statement, and a control thread with a timer. If the timer goes off and the SQL statement is still executing, the control thread can call otl_connect::cancel() on the same connect object that is being used to execute the SQL statement.
With OTL 4.0/DB2 CLI, the same worker thread technique can be used, only otl_stream::cancel() should be called on the otl_stream object.
In the future, if the OCI or the DB2 CLI provides similar functionality, this function may be implemented.
(const int prefetch_size=0);
|General constructor. It creates an otl_connect object and then calls the rlogon() function.|
on / connects to the database.
OTL 4.0/OCIx, OTL 4.0/ODBC, and OTL 4.0/DB2-CLI have different styles of connect strings:
The auto_commit parameter in this function is used for setting the connection "auto-commit" mode. This means that every single SQL statement, executed in the connection, will be automatically committed. This auto-commit mode has nothing to do with the otl_stream auto-commit mode. In order to set the mode to "auto-commit", the auto_commit parameter needs to be set to 1. By default, it is 0, meaning that "auto-commit" is off.
In Oracle 7, ODBC and DB2-CLI, this mode is called "auto-commit". In Oracle 8/8i/9i, it is called "commit-on-success." It is not quite clear why in Oracle 8 the term was changed to "commit-on-success" and pushed from the level of the connection down to the level of the SQL statement execution.
|void rlogon(Lda_Def* lda);|| Logs
on / connects to / attaches to the primary database
connection, which was made in Pro*C/C++ or any other
third-party library. This function works for OTL/OCI7
only, and it helps to make transition from the legacy
environment to the OTL environment smoother. See also
attaches to the primary database connection, which was made
in straight ODBC, DB2-CLI, or any other third-party (ODBC,
or DB2-CLI based) library. This function works for OTL/ODBC, DB2-CLI only, and it helps make
transition from the legacy environment to the OTL
|OTL/ODBC, DB2-CLI only. Under #define OTL_UNICODE_EXCEPTION_AND_RLOGON.
Logs on / connects to the database (DSN / database alias). This function works when Unicode ODBC driver functions are enabled (via the C++ standard #define UNICODE, #define _UNICODE). The function allows Unicode user names, passwords, and DSNs to be passed into the ODBC layer.
|OTL/ODBC, DB2-CLI only.
When !defined(OTL_UNICODE_EXCEPTION_AND_RLOGON) &&
(ODBCVER>=0x300 || defined(OTL_DB2_CLI)).
Logs on / connect to the database (DSN / database alias). This function is available when #define OTL_UNICODE_EXCEPTION_AND_LOGON is not enabled, for ODBC/ DB2 CLI drivers that support ODBC/DB2 CLI versions >= 300 (not older than 25-27 years old in 2018). The function allows one-byte character string user names, passwords, and DSNs to be passed into the ODBC/DB2 CLI layer. The function should be used when passwords have special characters.
|General constructor: attaches to the primary database connection, which was made in straight ODBC, DB2-CLI, or any other third-party (ODBC, or DB2-CLI based) library. This function works for OTL/ODBC, DB2-CLI only, and it helps make transition from the legacy environment to the OTL environment smoother.|
|OCI8 / 8i / 9i / 10g / 11g only. Logs on /
connect to / attach to the primary database connection,
which was made in Pro*C/C++ or any other third-party
library. It helps make integration of
OTL/OCI8/8i/9i/10/g/11g and the Pro*C/C++ environment smooth
and easy. In order to use this function in the Pro*C/C++
environment, #define OTL_ORA8_PROC needs to be set at the
beginning of the program. For more detail, see example 59
Connects to the database and set the following
connection attributes that are required by the Oracle XA
Library: server external name, server internal name.
|Logs off / disconnects from the database. In case if the primary connection was done in Pro*C/C++ (OTL/OCIx), this function just detaches from that connection without actually disconnecting from the database.|
to Oracle (OTL/OCI8/8i/9i/10g/11g only). This function
is a wrapper around the ServerAttach function of the
OCI8/9/10/11. The main reason to have separate functions to
attach to the server and then begin a session is
performance. For more detail, see Oracle's regular manuals.
These functions, along with the session_begin
functions, could be used for implementing a connection
management mechanism that is more efficient than the
traditional connection pooling. See also example 60.
tnsname (TNS alias from TNSNAMES.ORA file) can be specified. In order to connect to a remote Oracle server. For local connections, tnsname defaults to 0. The function attaches to the database server (local or remote). The following "server attachment" attributes that are required by the Oracle XA Library can be also specified.
|OTL/OCI8/8i/9i/10g/11g only. Detaches from Oracle|
|Begin / end Oracle 8 session (OTL/OCI8/8i/9i/10g/11g only). These functions complement the server attach/detach suite of functions, and are used to begin / end an Oracle 8 session. The main reason to have separate server attach/detach and session begin/end groups of function is performance. session_begin() is approximately 50-100 times faster than the normal rlogon(). These functions, along with the server_attach() and server_detach() functions, could be used for implementing a connection management mechanism that is several times more efficient [thus, more scalable] than the traditional connection pooling.|
|OTL/OCI8/8i/9i/10g/11g only. Ends Oracle
|OTL/OCI8/8i/9i/10g/11g only. Reopens session.
If a session was started via session_begin()
a given username/password and then closed via session_end(),
for the same username/password via session_reopen(). This
function takes advantage of the fact that the username and
password attributes of the OCI8/9/10/11 internal connect
structure have been already set by the previous
session_begin() function call. If a session has been started
via session_reopen(), it can be closed by calling
Also, see example 61
|Commits transaction. In the
otl_connect object, Oracle, ODBC and DB2-CLI connections, by
default, are set to auto-commit off. This means
that all transactions need to be committed by explicitly
calling the commit() function. It is not recommended to use
connections that are set to auto-commit on.
This function does not automatically flush any buffered data (a.k.a. otl_stream dirty buffers), so you must call otl_stream::flush() on any open INSERT / UPDATE / DELETE / stored procedure call (that modifies the database) first, otherwise the buffered data may not be written to the database in time for the commit. Note that there is an implicit call to flush() in the otl_stream destructor, unless otl_stream::set_flush(false) was called before the corresponding otl_stream was opened.
|void commit_nowait();||Under #define OTL_ORA10G_R2
Under #define OTL_ORA11G
Commits transaction asynchronously, same as commit and forget / commit with no wait. Available only for Oracle 10g Release 2 (Oracle 10.2) and higher. As soon as the rest of the database vendors release a similar feature, it will be implemented in OTL.
This function does not discard any buffered data (a.k.a. otl_stream dirty buffers), so you must call otl_stream::flush() on any open INSERT / UPDATE / DELETE / stored procedure call (that modifies the database) first, otherwise the buffered data may still be written to the database despite the rollback. Note that there is an implicit call to flush() in the otl_stream destructor, unless otl_stream::set_flush(false) was called before the corresponding otl_stream was opened.
|Sets otl_connect's auto-commit OFF and ON, within one open session/connect. These two functions are for partial backward compatibility only.|
|Sets the otl_stream pool size.
This function can be activated with #define OTL_STREAM_POOLING_ON,
used together with #define OTL_STL (or #define OTL_ACE, or #define OTL_UNICODE_STRING_TYPE).
If OTL_STREAM_POOLING_ON is defined in the program, the
function body gets included into the target code. Also, a
default stream pool gets allocated as part the otl_connect
object, even if the function doesn't get called. Therefore,
a call to the function will reallocate all the resources,
allocated by the default stream pool, or by previous calls
"SQLFetchScroll" mode, meaning that otl_stream instances
opened under a given otl_connect will use SQLFetchScroll()
instead of SQLExtendedFetch(). This function can be
activated with #define OTL_ODBC_USES_SQL_FETCH_SCROLL_WHEN_SPECIFIED_IN_OTL_CONNECT.
bool get_stream_pool_enabled_flag() const;
functions allow to enable / disable the stream pool at
runtime, as well as to get the "stream pool enabled" flag
(a.k.a. an ON/OFF switch). The functions can be activated
with #define OTL_STREAM_POOLING_ON,
used together with #define OTL_STL (or #define OTL_ACE). If
OTL_STREAM_POOLING_ON is defined in the program, the
function bodies get included into the target code.
"OTL stream pool enabled" flag is set to true by default.
(const int char_set=SQLCS_IMPLICIT);
function is available for OTL/OCI8i/9i/10g/11g under
only. In Unicode OTL, the Oracle database default or
national character set is allowed to be set:
SQLCS_IMPLICIT, and SQLCS_NCHAR are defined by the OCI header files.
Since this function is part of the otl_connect class, all otl_streams, that gets opened via a concrete connect object, will use the character set, that was set by the function.
The semantic of :var<char[...]...> declaration of string bind variables was extended to accomodate the Unicode strings. For example, char means a string of 19 double-byte Unicode characters, plus 19 double-byte possible surrogate characters, plus one double-byte null terminator. It sounds a little complicated, but that is just a reflection of a plethora of Unicode standards, coding techniques. It is strongly recommended to read the Unicode standards themselves, then the Oracle implementations the Unicode. By the way, Oracle 8i and 9i differ in that regard substantially.
|OTL/ODBC, OTL/DB2-CLI only.
Under #define OTL_THROWS_ON_SQL_SUCCESS_WITH_INFO
Sets the "OTL throws on SQL_SUCCESS_WITH_INFO"" flag. When the flag is set, and SQLExecDirect() / SQLExecute() function returns SQL_SUCCESS_WITH_INFO, OTL throws an otl_exception. This is useful for communicating more information from the SQL call, especially if the call is a call to a stored procedure, or a Transact-SQL batch that may return more diagnostic information than usual. The function is enabled only when #define OTL_THROWS_ON_SQL_SUCCES_WITH_INFO is defined.
|otl_connect& operator<<(const char* str);||Sends
to the otl_connect object. If the object is not connected to
a database then the string is a connection string in the
"userid/passwd@db" format and it makes the object connect to
the database. If the object is already connected, the string
is a static SQL statement that the connect object executes
|otl_connect& operator<<=(const char* str);||Sends
string to the otl_connect object. The connect object saves
the string for further use with operator >>().
The string is an SQL statement with placeholders that could
be sent to an otl_stream object. In other words, this
operator is a deferred SQL statement.
|otl_connect& operator>>(otl_stream& s);||Sends the SQL statement that was saved with operator <<= to an otl_stream object. It makes the otl_stream object open the SQL statement. If there was no SQL statement previously saved by the connect object, the connect object sends the following string to the otl_stream: "*** INVALID COMMAND ***"., which causes an SQL parse error in the otl_stream, which ends up in an otl_exception.|
SQL statement. The function returns the Rows Processed Count
The direct_exec() function may return the following values of the long int datatype:
| void syntax_check
(const char *sqlstm // SQL Statement
there is an SQL error.
|void set_connection_mode(const int connection_mode);||When
is enabled, OTL allows ODBC connections to more than one
database type to be made from the same program at the same
time without enabling any dababase specific #define's, which
would be in conflict.
Sets connection mode before otl_connect::rlogon() is called. See the connection mode list for mode detail.
The following is the list of available ODBC connection mode integer constants that can be used in calls to set_connection_mode() (ODBC driver specific restrictions like the stream buffer size / unsupported bulk interface still apply, see example 675 for more detail):
|int get_connection_mode();||Under #define OTL_ODBC_MULTI_MODE.
Gets connection mode for the otl_connect object.
set_prog_name(const char* prog_name);
||Under #define OTL_DB2_CLI.
Sets the program name that shows up as the "Application Name" column in the output of the "list applications" command in DB2 command line processsor. The function should be called before the connection to the database is made (before rlogon() is called), for example:
}; // end of otl_connect
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