Running a query as a SQL Developer script from java and save script's output

Question

I have a table at my db. I want fetch it as a .csv file using JAVA and ibatis.

I know that a quick way to do so using SQL Developer client would be to write the following query:

select /*csv*/* from employees

and execute it as a script at SQL Developer client. (As shown here)
I thought that com.ibatis.common.jdbc.ScriptRunner might suit my needs, but can't find a way to capture the script's output into .csv file.

Is it even possible to execute the query above from JAVA ?

Is there a faster way to do it? (sending a select query and parse its results is not an option for me.)

Thanks.

Answer 1

Well the best soution i found so far was to send the query:
SELECT EMP_NAME||', '|| EMP_LAST ||', '|| FROM EMP_TABLE
Map file:

<select id="testing" resultClass="java.lang.String">  
    SELECT EMP_NAME||', '|| EMP_LAST ||', '|| FROM EMP_TABLE  
 </select>

The query will return parsed strings as results.

"Joe, Smith , 1000"
"Dave, Devon , 1300"
...
"Zoee, Zinther , 900"

I tried 2 approaches:
1. rowHandler:

 long started1 = System.nanoTime();
 SelectToFile selectToFileRowHandler = new SelectToFile("test1.csv");
 sqlMap.queryWithRowHandler("map.testing", selectToFileRowHandler);
 long time1 = (System.nanoTime()-started1);
 System.out.println("with row handler: " + time1);

2. queryForList:

 long started2 = System.nanoTime();
 @SuppressWarnings("unchecked")
 List<String> lst = (List<String>)sqlMap.queryForList("map.testing");
 BufferedWriter bw = new BufferedWriter(new FileWriter("test2.csv"));
 for(String str : lst){
    bw.write(str);
 }
 long time2 = (System.nanoTime()-started2);
 System.out.println("with list: " + time2);

The results were:

with row handler: 2242707000
with list: 2455066000
rowhandler was faster by: 448629000 (approx 0.44 sec for 50K entries 7MB csv file.)

If anyone knows a faster way, i would happily test it, and post the results.

Answer 2

Please refer the link here to use spring batch.

You can use below Item Reader and Item writer

<bean id="pageReader" class="org.mybatis.spring.batch.MyBatisPagingItemReader" scope="step">
    <property name="sqlSessionFactory" ref="sqlSessionFactory" />
    <property name="queryId" value="getEmployee" />
    <property name="pageSize" value="1000" />
</bean>

<mapper namespace="com.kp.db.persistence.IEmpTableMapper">


    <select id="getEmployee" parameterType="EmpFieldMap">
        SELECT EMP_NAME, EMP_LAST FROM EMP_TABLE
    </select>
</mapper>




<bean id="cvsFileItemWriter" class="org.springframework.batch.item.file.FlatFileItemWriter" scope="step">
        <!-- write to this csv file -->
        <property name="resource" value="#{jobParameters['fileName']}" />
        <property name="shouldDeleteIfExists" value="true" />

        <property name="lineAggregator">


    <bean
                    class="org.springframework.batch.item.file.transform.DelimitedLineAggregator">
                    <property name="delimiter" value="," />

                    <property name="fieldExtractor">
                        <bean
                            class="org.springframework.batch.item.file.transform.BeanWrapperFieldExtractor">
                            <property name="names" value="empFirst, empLast" />
                        </bean>
                    </property>
                </bean>
            </property>

            <property name="headerCallback" ref="empHeader" />

        </bean>

And you need to configure Session factory.