how to compare csv file data and DB data

i suggest you create and temporary table in the database and export the data from CSV file to that temp table using SQL* loader and then compare.

as show in this doc.

http://stackoverflow.com/questions/10839856/using-sql-loader-in-oracle-to-import-csv-file

http://bytes.com/topic/oracle/answers/949173-excel-csv-data-oracle-tables-compare-data

Why going the long way round?!
Just take advantage of the EXTERNAL TABLE concepts ;-)
With the help of that, you can directly query from flat files as if you were accessing a normal DB table.
Here are the official docs:
http://docs.oracle.com/cd/B19306_01/server.102/b14215/et_concepts.htm

Here are some refs & examples:
http://www.oracle-base.com/articles/9i/external-tables-9i.php
http://psoug.org/reference/externaltab.html

I want do it java application.... I have written a sample  java application  ..
Before updating a record....
How i can compare excel value "10" if it exist in the database table identity.
then  it should change the value.....  if it donot find a similar value.. it should not update
in the database.........
 
let  us say
src/main/resources/ merge.csv

startid, endid
10         200
20          100


src/main/resources/schema-all.sql

DROP TABLE identity IF EXISTS;

CREATE TABLE identity(
    startid VARCHAR(10) IDENTITY NOT NULL PRIMARY KEY,
    endid  VARCHAR(10),
    
);

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package hello;

public class identity {
    private String endid;
    private String firstid;

    public identity() {

    }

    public Identity(String startid, String endid) {
        this.startid = startid;
        this.endid = endid;
    }

    public void setStartid(String startid) {
        this.firstName = firstName;
    }

    public String getStartid() {
        return firstid;
    }

    public String getLastid() {
        return lastid;
    }

    public void setLastid(String lastid) {
        this.lastid = lastid;
    }

    @Override
    public String toString() {
        return "startid: " + startid + ", lastid: " + lastid;
    }

}

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@Configuration
@EnableBatchProcessing
public class BatchConfiguration {

    // tag::readerwriterprocessor[]
    @Bean
    public ItemReader<Identity> reader() {
        FlatFileItemReader<Identity> reader = new FlatFileItemReader<Identity>();
        reader.setResource(new ClassPathResource("merge.csv"));
        reader.setLineMapper(new DefaultLineMapper<Identity>() {{
            setLineTokenizer(new DelimitedLineTokenizer() {{
                setNames(new String[] { "startid", "lastid" });
            }});
            setFieldSetMapper(new BeanWrapperFieldSetMapper<Identity>() {{
                setTargetType(Identity.class);
            }});
        }});
        return reader;
    }

   

    @Bean
    public ItemWriter<Identity> writer(DataSource dataSource) {
        JdbcBatchItemWriter<Identity> writer = new JdbcBatchItemWriter<Identity>();
        writer.setItemSqlParameterSourceProvider(new BeanPropertyItemSqlParameterSourceProvider<Person>());
        writer.setSql(""UPDATE Identiy SET endid= ? WHERE startid = ?";");
        writer.setDataSource(dataSource);
        return writer;
    }
    // end::readerwriterprocessor[]

    // tag::jobstep[]
    @Bean
    public Job importUserJob(JobBuilderFactory jobs, Step s1) {
        return jobs.get("importUserJob")
                .incrementer(new RunIdIncrementer())
                .flow(s1)
                .end()
                .build();
    }

    @Bean
    public Step step1(StepBuilderFactory stepBuilderFactory, ItemReader<Person> reader,
            ItemWriter<Person> writer, ItemProcessor<Person, Person> processor) {
        return stepBuilderFactory.get("step1")
                .<Person, Person> chunk(10)
                .reader(reader)
                .processor(processor)
                .writer(writer)
                .build();
    }
    // end::jobstep[]

    @Bean
    public JdbcTemplate jdbcTemplate(DataSource dataSource) {
        return new JdbcTemplate(dataSource);
    }

}

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i did not got any solution on spring batch  this from the experts