Comparing Two Oracle Tables of Different Databases in Java: A Comprehensive Guide

Comparing Two Oracle Tables of Different Databases in Java

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As a technical blogger, I’ll guide you through the process of comparing two Oracle tables from different databases using Java. We’ll explore various approaches and provide code examples to make it easier for you to understand.

Background

In this scenario, we have two separate databases with similar table structures but containing identical data. Our goal is to compare these tables to ensure that any updates made in one database are reflected in the other.

Approach 1: Using Separate Connections and Statements

One approach to comparing two Oracle tables from different databases is by establishing separate connections and statements for each database.

Code Example

public boolean isSame(){
    try{
        Connection con = DriverManager.getConnection(URL, userName, pass);
        Connection con2 = DriverManager.getConnection(URL, userName, pass);
        
        Statement stmt = con.createStatement();
        Statement stmt2 = con2.createStatement();
        
        ResultSet rs = stmt.executeQuery(SQL_Statement);
        ResultSet rs2 = stmt2.executeQuery(SQL_Statement);
        
        int count=0;
        int rowCount= 0;
        while (rs.next())
        {
            while(rs2.next()){
                String Customer = rs.getString(1);
                String Customer2 = rs2.getString(1);
                if(Customer.equals(Customer2)){
                    return true;
                }
            }
        }
    } catch(Exception e){
        System.out.println(e.toString());
    }
    return false; 
}

Explanation

In this example, we establish two separate connections to the two databases using DriverManager.getConnection(). We then create statements and result sets for each connection. Finally, we iterate through both result sets simultaneously using nested loops to compare the values.

Approach 2: Using a Single Connection with Different Statements

Another approach is to use a single connection to both databases, but create separate statements and result sets for each database.

Code Example

public boolean isSame(){
    try{
        Connection con = DriverManager.getConnection(URL, userName, pass);
        
        Statement stmt1 = con.createStatement();
        ResultSet rs1 = stmt1.executeQuery(SQL_Statement1);
        
        Statement stmt2 = con.createStatement();
        ResultSet rs2 = stmt2.executeQuery(SQL_Statement2);
        
        int count=0;
        int rowCount= 0;
        while (rs1.next())
        {
            while(rs2.next()){
                String Customer = rs1.getString(1);
                String Customer2 = rs2.getString(1);
                if(Customer.equals(Customer2)){
                    return true;
                }
            }
        }
    } catch(Exception e){
        System.out.println(e.toString());
    }
    return false; 
}

Explanation

In this example, we use a single connection to both databases. We then create separate statements and result sets for each database using con.createStatement(). Finally, we iterate through both result sets simultaneously using nested loops to compare the values.

Approach 3: Using Sets to Compare Data

We can also use sets to compare data between the two tables.

Code Example

public boolean isSame(){
    try{
        Connection con = DriverManager.getConnection(URL, userName, pass);
        
        Statement stmt = con.createStatement();
        ResultSet rs = stmt.executeQuery(SQL_Statement);
        
        Set<String> set1 = new HashSet<>();
        while (rs.next()){
            set1.add(rs.getString(1));
        }
        
        Statement stmt2 = con.createStatement();
        ResultSet rs2 = stmt2.executeQuery(SQL_Statement);
        
        Set<String> set2 = new HashSet<>();
        while (rs2.next()){
            set2.add(rs2.getString(1));
        }
        
        if(set1.equals(set2)){
            return true;
        } else {
            return false;
        }
    } catch(Exception e){
        System.out.println(e.toString());
    }
}

Explanation

In this example, we create a set to store the values from one result set and another set to store the values from the other result set. We then compare these two sets using the equals() method.

Conclusion

Comparing two Oracle tables of different databases can be achieved in various ways depending on your specific requirements. By using separate connections, statements, and result sets, or by utilizing sets to compare data, you can ensure that any updates made in one database are reflected in the other.

I hope this article has provided a comprehensive guide to comparing two Oracle tables from different databases using Java. If you have any further questions or need additional assistance, please don’t hesitate to ask.

Last modified on 2024-01-25