How to Efficiently Get Distinct Values from a Specific Field in LINQ?

Getting Distinct Values in LINQ Based on a Table Field

In LINQ, the distinct operator is commonly used to eliminate duplicate records from a data source. However, when dealing with large datasets, it can become inefficient if you only need to filter results based on a specific field.

To address this issue, consider the following query:

var query = (from r in table1
orderby r.Text
select r).distinct();

While this query will sort the results by the Text field, it does not guarantee distinct results solely based on that field.

For true distinct results, you can use the following approach:

table1.GroupBy(x => x.Text).Select(x => x.FirstOrDefault());

This query groups the table by the Text field, essentially splitting the dataset into smaller groups based on unique Text values. Subsequently, it selects only the first row from each group, effectively returning distinct records without requiring the overhead of sorting the entire dataset.

By using this approach, you can efficiently retrieve distinct values from a table while focusing only on the desired field.

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