net.sourceforge.jtds.jdbc

Notes:

1. For maximum performance use the scroll insensitive result set type.
2. As the result set is cached in memory this implementation is limited to small result sets.
3. Updateable or scroll sensitive result sets are limited to selects which reference one table only.
4. Scroll sensitive result sets must have primary keys.
5. Updates are optimistic.

Implementation note:

1. This implementation stores the CLOB data in a byte array managed by the BlobBuffer class.

Implementation notes:

1. Environment setting code carried over from old jTDS otherwise generally a new implementation of Connection.
2. Connection properties and SQLException text messages are loaded from a properties file.
3. Character set choices are also loaded from a resource file and the original Encoder class has gone.
4. Prepared SQL statements are converted to procedures in the prepareSQL method.
5. Use of Stored procedures is optional and controlled via connection property.
6. This Connection object maintains a table of weak references to associated statements.

This class also provides static utility methods for Properties and Settings objects.

To add new properties to the jTDS driver, do the following:

1. Add prop.foo and prop.desc.foo properties to Messages.properties.
2. Add a static final default field to DefaultProperties .
3. Update DefaultProperties.addDefaultProperties(java.util.Properties) to set the default.
4. Update Driver.createChoicesMap() and DriverUnitTest.test_getPropertyInfo_Choices() if the property has a specific set of inputs, e.g., "true" and "false", or "1" and "2".
5. Update Driver.createRequiredTrueMap() and DriverUnitTest.test_getPropertyInfo_Required() if the property is required.
6. Add a new test to DefaultPropertiesTestLibrary for the new property.

Implementation note:

This is basically the code from the original jTDS driver. Main changes relate to the need to support the new ResultSet implementation.

TODO: Many of the system limits need to be revised to more accurately reflect the target database constraints.

Implementation notes:

1. Generally a simple subclass of Statement mainly adding support for the setting of parameters.
2. The stream logic is taken over from the work Brian did to add Blob support to the original jTDS.
3. Use of Statement specific method calls eg executeQuery(sql) is blocked by this version of the driver.

NB.

For Sybase it is usually possible to obtain true parameter data for prepared statements.

Based on the code originally written by Doug Lea.

Constraints and assumptions:

1. Callers will not attempt to read from the server without issuing a request first.
2. The end of a server reply can be identified as byte 2 of the header is non zero.

1. This code will discard unread server data if a new request is issued. Currently the higher levels of the driver attempt to do this but may be we can just rely on this code instead.
2. A cancel can be issued by a caller only if the server is currently sending data for the caller otherwise the cancel is ignored.
3. Cancel packets on their own are returned as extra records appended to the previous packet so that the TdsCore module can process them.