Question

I have a Java-application that loads data from a legacy file format into an SQLite-Database using JDBC. If the database file specified does not exist, it is supposed to create a new one. Currently the schema for the database is hardcoded in the application. I would much rather have it in a separate file as an SQL-Script, but apparently there is no easy way to execute an SQL-Script though JDBC. Is there any other way or a pattern to achieve something like this?

Answer 1

Your sentence “there is now easy way to execute an SQL-Script though JDBC” confused me for a minute, but I reckon you are saying “there is no easy way”. 🙂

Based on what others have said, yes… the perfect world scenario is to use an ORM tool, like Hibernate, but I also understand the fact when you are dealing with legacy stuff at work, your team may not want to spend too much time refactoring that project.

I agree that you should refactor out the database schema into a separate file. You can actually execute the SQL script using JDBC. I do that all the time when I run my certain testcases.

Here’s how I do it. I use SQL Server database in my case. So, you need to tweak the code to fit your needs.

String ddl = ... // load your SQL script file into this string
String delimiter = "GO"; // in my case, SQL Server uses GO as delimiter, you use whatever you want here.


private void executeDDL(String ddl, String delimiter) {
    Connection con = null;

    try {
        con = ... // get the connection

        // enable transaction
        con.setAutoCommit(false);

        Statement statement = con.createStatement();

        // for every DDL statement, execute it
        for (String sql : ddl.split(delimiter)) {
            if (StringUtils.isNotBlank(sql)) {
                statement.executeUpdate(sql);
            }
        }

        statement.close();
        con.commit();
    }
    catch (Exception e) {
        e.printStackTrace();
    }
    finally {
        try {
            con.close();
        }
        catch (Exception ignored) {
        }
    }
}