If you’re working with JDBC (Java Database Connectivity) and retrieving data from a database, you might have encountered the error message ‘ResultSet is positioned before the first row.’ This issue commonly arises when trying to read data from a ResultSet without properly positioning the cursor.
In this topic, we will explore what causes this error, how ResultSet works, and the best practices to avoid this issue while working with databases in Java.
What Does ‘ResultSet Is Positioned Before the First Row’ Mean?
A ResultSet in Java represents the result of a query executed on a database. When a query is executed using Statement.executeQuery(), the returned ResultSet starts in a default position-before the first row. This means that you need to explicitly move the cursor to the first row before accessing data.
The error occurs when you try to read column values from ResultSetwithout first calling next() to move the cursor to the first row.
Example That Causes the Error:
ResultSet rs = statement.executeQuery('SELECT * FROM users');// Attempting to access data before moving the cursorSystem.out.println(rs.getString('username')); // ERROR: ResultSet is positioned before the first rowSince ResultSet starts before the first row, you must call rs.next() before accessing any data.
How to Fix the Error
1. Move the Cursor to the First Row Using next()
To correctly retrieve data from the ResultSet, use rs.next() before accessing column values:
ResultSet rs = statement.executeQuery('SELECT * FROM users');if (rs.next()) { // Moves the cursor to the first rowSystem.out.println(rs.getString('username')); // Now it works} else {System.out.println('No data found.');}The rs.next() method returns true if there is a row to move to; otherwise, it returns false.
2. Use a while Loop for Multiple Rows
If your query returns multiple rows, use a while loop to iterate through them:
ResultSet rs = statement.executeQuery('SELECT * FROM users');while (rs.next()) { // Iterates through all rowsSystem.out.println('Username: ' + rs.getString('username'));}This ensures that you only access data after the cursor has moved to a valid row.
3. Check If the ResultSet Has Any Rows Using isBeforeFirst()
If you want to verify whether the ResultSet contains data before trying to access it, use rs.isBeforeFirst().
ResultSet rs = statement.executeQuery('SELECT * FROM users');if (!rs.isBeforeFirst()) { // No data foundSystem.out.println('No records found.');} else {while (rs.next()) {System.out.println('Username: ' + rs.getString('username'));}}This prevents the error by checking whether the ResultSet contains any rows before attempting to move the cursor.
4. Using first() for Scrollable ResultSets
If you are using a scrollableResultSet, you can use rs.first() instead of rs.next() to move directly to the first row:
Statement stmt = connection.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);ResultSet rs = stmt.executeQuery('SELECT * FROM users');if (rs.first()) { // Moves directly to the first rowSystem.out.println('Username: ' + rs.getString('username'));} else {System.out.println('No data found.');}However, rs.first() only works if the ResultSet is scrollable. By default, ResultSet is forward-only, so using first() on a non-scrollable ResultSet will throw an error.
Understanding ResultSet Cursor Positioning
1. Default Position of ResultSet
When a ResultSet is created, the cursor is positioned before the first row. You must explicitly move it using rs.next() before reading data.
[START] → Row 1 → Row 2 → Row 3 → [END]2. Methods for Moving the Cursor
| Method | Description |
|---|---|
next() |
Moves the cursor forward by one row. Returns false if no more rows exist. |
previous() |
Moves the cursor backward by one row (only for scrollable ResultSet). |
first() |
Moves the cursor directly to the first row (only for scrollable ResultSet). |
last() |
Moves the cursor directly to the last row (only for scrollable ResultSet). |
isBeforeFirst() |
Checks if the cursor is before the first row. |
isAfterLast() |
Checks if the cursor is after the last row. |
Common Mistakes That Cause the Error
1. Trying to Access Data Without Calling next()
❌ Incorrect Code:
ResultSet rs = statement.executeQuery('SELECT * FROM users');System.out.println(rs.getString('username')); // ERROR✅ Corrected Code:
ResultSet rs = statement.executeQuery('SELECT * FROM users');if (rs.next()) {System.out.println(rs.getString('username'));}2. Forgetting to Handle an Empty ResultSet
❌ Incorrect Code:
ResultSet rs = statement.executeQuery('SELECT * FROM users');rs.next(); // What if there are no rows?System.out.println(rs.getString('username')); // ERROR✅ Corrected Code:
ResultSet rs = statement.executeQuery('SELECT * FROM users');if (!rs.isBeforeFirst()) { System.out.println('No records found.');} else {while (rs.next()) {System.out.println(rs.getString('username'));}}3. Using first() on a Non-Scrollable ResultSet
❌ Incorrect Code:
ResultSet rs = statement.executeQuery('SELECT * FROM users');rs.first(); // ERROR: Default ResultSet is not scrollableSystem.out.println(rs.getString('username'));✅ Corrected Code:
Statement stmt = connection.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);ResultSet rs = stmt.executeQuery('SELECT * FROM users');if (rs.first()) {System.out.println(rs.getString('username'));}Best Practices to Avoid ‘ResultSet Is Positioned Before the First Row’
✅ Always call rs.next() before accessing data.
✅ Use a while loop to iterate through multiple rows.
✅ Use isBeforeFirst() to check if the ResultSet contains data.
✅ If you need a scrollable ResultSet, create it explicitly.
✅ Close the ResultSet and Statement after use to prevent memory leaks.
The ‘ResultSet is positioned before the first row’ error occurs because a ResultSet starts in a position before the first row by default. To avoid this issue, always call rs.next() before accessing data.
Using best practices like checking for empty results, using loops correctly, and handling cursor movements properly will ensure smooth database interactions in Java applications.