What are the tools and methods for transferring data between databases?

The following tools and methods are used for transferring data between databases:

• Export/Import of data — exporting data from one database in CSV, SQL dump, or other formats and then importing into another database.
• ETL processes (Extract, Transform, Load) — extracting data, transforming it, and loading it into the target database using specialized tools (e.g., Apache NiFi, Talend).
• Replication — setting up data synchronization between databases in real-time or with delay.
• JDBC/ODBC — programmatic access to databases for reading and writing data through Java applications.
• Specialized migration tools — such as Flyway, Liquibase for migrating schemas and data.

Example in Java using JDBC to copy data from one table to another:

Connection sourceConn = DriverManager.getConnection(sourceUrl, user, pass);
Connection targetConn = DriverManager.getConnection(targetUrl, user, pass);

Statement stmt = sourceConn.createStatement();
ResultSet rs = stmt.executeQuery("SELECT * FROM source_table");

PreparedStatement ps = targetConn.prepareStatement("INSERT INTO target_table (col1, col2) VALUES (?, ?)");

while (rs.next()) {
    ps.setString(1, rs.getString("col1"));
    ps.setString(2, rs.getString("col2"));
    ps.executeUpdate();
}

rs.close();
stmt.close();
ps.close();
sourceConn.close();
targetConn.close();