Question

I’m using postgresql to host my database. In my database, I have a table say xyz whose structure is as shown below

id    content    folder
1     hello      Inbox
2     hi         Sent

I want to export this table to CSV using my java program. The code snippet is below

Connection connection2  = new ServerDBConnect().getConnection();
PreparedStatement statement = connection2.prepareStatement("copy (SELECT * FROM xyz WHERE folder=? ) to 'C:/export.csv' delimiter ','");
statement.setString(1, FOLDER_SELECTED); //Here, FOLDER_SELECTED=Inbox
statement.execute();

When I execute this code, I’m getting SQLException saying

ERROR: there is no parameter $1

If I execute the code without folder specified ("copy (SELECT * FROM xyz) to 'C:/export.csv' delimiter ','")), the code works fine.

What am I doing wrong here? How to go about this problem?

Note: If I execute the query (copy (SELECT * FROM xyz WHERE folder='Inbox' ORDER BY time) to 'G:/export.csv' delimiter ',') directly in the Postgresql SQL console, I’m getting the desired output.

Please help

Answer 1

Ah

I finally found the answer myself.

Small change in the query gave me the desired result

The query is suppose to be like this

Connection connection2  = new ServerDBConnect().getConnection();
PreparedStatement statement = connection2.prepareStatement("copy (SELECT * FROM xyz WHERE folder='" + FOLDER_SELECTED + "' ) to 'C:/export.csv' delimiter ','");

This was driving me crazy, but finally done 🙂