How Do I Iterate Through a Java ResultSet to Extract Data from a Grouped Query?

Looping Through Java Result Sets

In Java, a ResultSet provides a tabular view of database query results. Iterating through the results is a common operation. Let's consider the following example:

You have a query that groups rows based on the "rlink_id" column and counts the occurrences of each unique value:

String querystring1 = "SELECT rlink_id, COUNT(*)"
                   + "FROM dbo.Locate  "
                   + "GROUP BY rlink_id ";

The corresponding "rlink_id" table contains the following data:

Sid        lid
3           2
4           4
7           3
9           1

To loop through the results of this query using a ResultSet, you can utilize the following steps:

1. Create two ArrayLists, one for storing the "sid" values and another for the "lid" values:

List<String> sids = new ArrayList<>();
List<String> lids = new ArrayList<>();

2. Execute the query and retrieve the ResultSet:

Statement stmt = yourconnection.createStatement();
ResultSet rs4 = stmt.executeQuery(query);

3. Iterate through the ResultSet while there are any remaining rows:

while (rs4.next()) {
    sids.add(rs4.getString(1));
    lids.add(rs4.getString(2));
}

4. Close the Statement object after processing the results:

stmt.close();

5. Convert the ArrayLists into arrays for further processing:

String show[] = sids.toArray(sids.size());
String actuate[] = lids.toArray(lids.size());

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