How to Efficiently Get the Size of a Java `java.sql.ResultSet`?

Determining the Row Count of a java.sql.ResultSet

While seemingly simple, directly obtaining the number of rows in a java.sql.ResultSet isn't supported by built-in methods like size() or length(). Here are two efficient solutions:

*Method 1: `COUNT()` SQL Query**

The most efficient way is to execute a separate SELECT COUNT(*) FROM ... query against your database. This directly retrieves the row count without needing to fetch the entire result set.

Method 2: Cursor Positioning

This approach leverages the ResultSet cursor:

<code class="language-java">int rowCount = 0;
if (rs != null) {
    try {
        rs.last();
        rowCount = rs.getRow();
    } catch (SQLException e) {
        // Handle SQLException appropriately
        e.printStackTrace(); // Or log the exception
    }
}</code>

This moves the cursor to the last row and then retrieves its row number, providing the total row count. Error handling is crucial here to manage potential SQLExceptions.

Both methods avoid iterating through all rows, offering performance advantages over less efficient alternatives. Choose the method best suited to your application's needs and context.

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