How to get the number of columns from a JDBC ResultSet?

Question

I am using CsvJdbc (it is a JDBC-driver for csv-files) to access a csv-file. I don\'t know how many columns the csv-file contains. How can I get the number of columns? Is th

Answer 1

Number of a columns in the result set you can get with code (as DB is used PostgreSQL):

//load the driver for PostgreSQL
Class.forName("org.postgresql.Driver");

String url = "jdbc:postgresql://localhost/test";
Properties props = new Properties();
props.setProperty("user","mydbuser");
props.setProperty("password","mydbpass");
Connection conn = DriverManager.getConnection(url, props);

//create statement
Statement stat = conn.createStatement();

//obtain a result set
ResultSet rs = stat.executeQuery("SELECT c1, c2, c3, c4, c5 FROM MY_TABLE");

//from result set give metadata
ResultSetMetaData rsmd = rs.getMetaData();

//columns count from metadata object
int numOfCols = rsmd.getColumnCount();

But you can get more meta-informations about columns:

for(int i = 1; i <= numOfCols; i++)
{
    System.out.println(rsmd.getColumnName(i));
}

And at least but not least, you can get some info not just about table but about DB too, how to do it you can find here and here.