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The ODBC interface deals with a single ODBC environment with multiple simultaneous connections. The predicates in this section deal with connection management.
aliasoption is used. In addition to the options below, options applicable to odbc_set_connection/2 may be provided.
once(default if an
aliasis provided), a second call to open the same DSN simply returns the existing connection. If
multiple(default if there is no alias name), a second connection to the same data-source is opened.
true, use Microsoft SQL server 2005 mars mode. This is support for multiple concurrent statements on a connection without requiring the dynamic cursor (which incurs an astounding 20-50x slowdown of query execution!!). MARS is a new feature in SQL2k5 apparently, and only works if you use the native driver. For the non-native driver, specifying that it is enabled will have absolutely no effect.
'3.0'. The other supported value is
The following example connects to the WordNet1An
SQL version of WordNet is available from http://wordnet2sql.infocity.cjb.net/
 database, using
the connection alias
wordnet and opening the connection
open_wordnet :- odbc_connect('WordNet', _, [ user(jan), password(xxx), alias(wordnet), open(once) ]).
Whenever possible, applications should use odbc_connect/3. If you need this predicate, please check the documentation for SQLDriverConnect() and the documentation of your driver.bugFacilities to deal with prompted completion of the driver options are not yet implemented.
read, tell the driver we only access the database in read mode. If
update(default), tell the driver we may execute update commands.
true(default), each update statement is committed immediately. If
false, an update statement starts a transaction that can be committed or rolled-back. See section 2.3 for details on transaction management.
dynamicmakes it possible to have multiple active statements on the same connection with Microsoft SQL server. Other values are
unicodewhile on other platforms it is
utf8. Below, the *A() functions refer to the `ansi' ODBC functions that exchange bytes and the *W() functions refer to the `unicode' ODBC functions that exchange UCS-2 characters.
false), statements returning
SQL_SUCCESS_WITH_INFOsucceed without printing the info. See also section 2.7.1.
$null$. NullSpecifier is an arbitrary Prolog term, though the implementation is optimised for using an unbound variable, atom and functor with one unbound variable. The representation
null(_)is a commonly used alternative.
The specified default holds for all statements executed on this connection. Changing the connection default does not affect already prepared or running statements. The null-value can also be specified at the statement level. See the option list of odbc_query/4.
Name(Value). If Property is unbound all defined properties are enumerated on backtracking. Currently the following properties are defined.
dynamic. See odbc_set_connection/2.