### Setting up the JDBC driver

To connect to a database via a JDBC driver:

1. Install the JDBC driver according to the instructions provided by the JDBC driver provider.
2. Edit JReport.bat/JReport.sh or setenv.bat/setenv.sh in `<designer_install_root>\bin`, by appending the class path for the JDBC driver.

Note: The step for appending the class path is very important. The same changes made to JReport Designer’s class path must be made to the class path for JReport Enterprise Server too. A missing JDBC driver in the JReport start-up batch file or command line will result in a "ClassNotFoundError message" when you try to run a report. Meanwhile, if you want to use the DHTML Preview feature in JReport Designer, you also need to append the class path for the JDBC driver to setenv.bat/setenv.sh in `<designer_install_root>\server\bin.`

The following are two examples of setting up the JDBC driver.

Example 1: Installing a Sybase JDBC driver

1. Install Sybase JDBC driver Jconnect.class, and run the SQL file sql_server.sql to create the JDBC metadata tables (refer to the user's guide of Sybase installation for further details).
2. Modify setenv.bat by appending the archive file path of the driver to the set ADDCLASSPATH system variable:

   `set REPORTHOME=C:\JReport\Designer
   set JAVAHOME=C:\j2sdk1.4.2_01
   set ADDCLASSPATH=c:\jconnect\classes`

   Or edit JReport.bat/JReport.sh in `C:\JReport\Designer\bin` (`/opt/JReport/Designer/bin`) by appending the archive file path of the driver to the class path:

   Change: `... classpath "%REPORTHOME%\lib\SwingDesigner.jar;%REPORTHOME%\lib\resources.jar;..."`
   To: `... classpath "%REPORTHOME%\lib\SwingDesigner.jar;c:\jconnect\classes;%REPORTHOME%\lib\resources.jar;..."`

Example 2: Installing an Oracle JDBC driver

1. Install Oracle JDBC driver classes12.zip.
2. Modify setenv.bat by appending the archive file path of the driver to the set ADDCLASSPATH system variable:

   `set REPORTHOME=C:\JReport\Designer
   set JAVAHOME=C:\j2sdk1.4.2_01
   set ADDCLASSPATH=c:\orc\thin\lib\classes12.zip`

   Or edit JReport.bat/JReport.sh in `C:\JReport\Designer\bin` (`/opt/JReport/Designer/bin`) by appending the archive file of the Oracle thin driver to the class path:

   Change: `... classpath "%REPORTHOME%\lib\SwingDesigner.jar;%REPORTHOME%\lib\resources.jar;..."`
   To: `... classpath "%REPORTHOME%\lib\SwingDesigner.jar;c:\orc\thin\lib\classes12.zip;%REPORTHOME%\lib\resources.jar;..."`

#### Limiting the size of the fetch data buffer

If you are using a database which supports the JDBC method Statement.setFetchSize(), you can request the database retrieve a specified number of rows in each read instead of all rows which minimizes memory usage which can improve performance. It can also avoid Java heap out of memory errors when doing large queries. JReport provides a property setFetchSize in the JdbcDriversConfig.properties file for you to do this, which is located in the `<install_root>\bin` directory.

The following is an example of setting the setFetchSize property in the JdbcDriversConfig.properties file and detailed description of each property:

    DriverName_D1 = MySQL-AB JDBC Driver
    Vendor_D1 = MySql.com
    Version_D1 = 3.0.8-stable ($Date: 2011/05/20 02:20:13 $, $Revision: 1.1 $)
    setFetchSize_D1 = 5000

- DriverName_[Name]
  Database driver name that should be used to establish a connection. You can use connection.getMetaData().getDriverName() to obtain the value.
- Vendor_[Name]
  The vendor of current JDBC driver. It is a string value.
- Version_[Name]
  The version of current JDBC driver. You can use connection.getMetaData().getDriverVersion() to obtain the value.
- setFetchSize_[Name]
  The number of rows retrieved in each buffer from the database. It is an Integer value that should be larger than 0 and less than or equal to getMaxRows(). The default value is different according to the driver in use. You can refer to your own database driver specification.
- _[Name]
  It is a user-defined name used to mark a group of driver settings different from the other groups.

#### Specifying where to implement the maximum query run time and number of records

In the JdbcDriversConfig.properties file, you can also specify where the properties, Maximum Rows and Maximum Duration, will be implemented, on JReport side or on the database side. For details about usage of these two properties, see Limiting the query run time and number of records.

The following is an example of setting the two properties:

    DriverName_D2 = Oracle JDBC driver
    Vendor_D2 = Oracle
    Version_D2 = 9.2.0.3.0
    supportMaxRowPushDown_D2 = true
    supportMaxDurPushDown_D2 = true

- DriverName_[Name]
  Database driver name that should be used to establish a connection. You can use connection.getMetaData().getDriverName() to obtain the value.
- Vendor_[Name]
  The vendor of current JDBC driver. It is a string value.
- Version_[Name]
  The version of current JDBC driver. You can use connection.getMetaData().getDriverVersion() to obtain the value.
- SupportMaxRowPushDown_[Name]
  Specifies where the property Maximum Rows will be implemented, on JReport side or on the database side. By default, it is set to true, which means the property will take effect on the database side. If it is set to false, the property will take effect on JReport side.
- SupportMaxDurPushDown_[Name]
  Specifies where the property Maximum Duration will be implemented, on JReport side or on the database side. By default, it is set to true, which means the property will take effect on the database side. If it is set to false, the property will take effect on JReport side.
- _[Name]
  It is a user-defined name used to mark a group of driver settings different from the other groups.

Notes:

- If there are more than one group with the same group marking name, the last group will be adopted.
- If the sign # is seen before "DriverName" of a group, or if setFetchSize is given a negative value, the whole group will be disabled.