Kotlin JDBC – RowSet Interface

The RowSet interface is a sub-interface of ResultSet and is used provide finer grade control over JDBC result sets. The RowSet interface has its own sub-interfaces that provide different features depending on the type of interface.

RowSet Sub-Interfavces

Interface Brief Description
JdbcRowSet A RowSet that is capable of being used as a JavaBeans component. The JdbcRowSet maintains a connection to the underlying database and makes the ResultSet scrollable and updateable.
CachedRowSet Caches rows in memory, allowing for the application to work on the ResultSet without maintaing an active connection to the database.
WebRowSet : CachedRowSet An extension of CachedRowSet, the WebRowSet provides XML capabilities
JoinRowSet : WebRowSet Extends WebRowSet to provide SQL JOIN capabilities.
FilterRowSet : WebRowSet Extends WebRowSet to provide filtering capabilities

Example Program

Below is an example program that demonstrates how to create an instance of RowSet.

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>OCJP-DB</groupId>
    <artifactId>ocjpdb</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <kotlin.version>1.2.10</kotlin.version>
        <main.class>stonesoupprogramming.MainKt</main.class>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.apache.derby</groupId>
            <artifactId>derby</artifactId>
            <version>10.14.1.0</version>
        </dependency>
        <dependency>
            <groupId>org.jetbrains.kotlin</groupId>
            <artifactId>kotlin-stdlib-jre8</artifactId>
            <version>${kotlin.version}</version>
        </dependency>
        <dependency>
            <groupId>org.jetbrains.kotlin</groupId>
            <artifactId>kotlin-test</artifactId>
            <version>${kotlin.version}</version>
            <scope>test</scope>
        </dependency>

    </dependencies>

    <build>
        <sourceDirectory>src/main/kotlin</sourceDirectory>
        <plugins>
            <plugin>
                <groupId>org.jetbrains.kotlin</groupId>
                <artifactId>kotlin-maven-plugin</artifactId>
                <version>${kotlin.version}</version>
                <executions>
                    <execution>
                        <id>compile</id>
                        <phase>compile</phase>
                        <goals>
                            <goal>compile</goal>
                        </goals>
                    </execution>
                    <execution>
                        <id>test-compile</id>
                        <phase>test-compile</phase>
                        <goals>
                            <goal>test-compile</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <jvmTarget>1.8</jvmTarget>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-jar-plugin</artifactId>
                <version>2.6</version>
                <configuration>
                    <archive>
                        <manifest>
                            <addClasspath>true</addClasspath>
                            <mainClass>${main.class}</mainClass>
                        </manifest>
                    </archive>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>exec-maven-plugin</artifactId>
                <version>1.2.1</version>
                <executions>
                    <execution>
                        <phase>test</phase>
                        <goals>
                            <goal>java</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <mainClass>${main.class}</mainClass>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

EmployeesRowset.kt

package stonesoupprogramming

import javax.sql.rowset.RowSetProvider

fun main (args : Array<String>){
    val rowSet  = RowSetProvider.newFactory().createWebRowSet()

    with(rowSet){
        //Connection information
        url = "jdbc:derby:stonesoup;create=true"
        username = "admin"
        password = "pw"

        //Command to execute against the database
        command = "SELECT * FROM BURGERS.EMPLOYEES"

        //Execute the command
        execute()

        //Output XML to standard out
        writeXml(System.out)
    }
}

Explanation

This program queries a table in the database and prints the XML to the standard out. We get an instance of WebRowSet by calling createWebRowSet() on line 6. Note that if we wanted a different kind of RowSet, we would just use the corresponding method on RowSetProvider. For example, if we wanted a JdbcRowSet, we would use createJdbcRowSet() instead of createWebRowSet().

The result is a RowSet object. Once we have a RowSet object, we start by populating its properties to establish a connection to the database. In this case, we pass a JDBC connection string, a username, and a password. Next, we set the command property with a SQL string.

The SQL is executed when call the execute() method. A connection is established to the database and then the RowSet object is populated with the results. Since we are using a WebRowSet, we can write the results to XML. The example program passes System.out as the output stream and the results appear on the console.

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