How Can I Retrieve Only Unique Records from a SQL Table?

Extracting Unique Data from SQL Tables

Dealing with duplicate entries in a SQL table? This guide shows you how to efficiently retrieve only the unique records. The DISTINCT keyword is your key to success.

Let's say you have a table with redundant data in a particular column (as illustrated in the example image). To isolate unique values from this column, use this SQL syntax:

SELECT DISTINCT column_name
FROM table_name;

For example, SELECT DISTINCT column2 FROM table_name will return only the unique entries from column2, removing duplicates such as "item1" from the sample table.

Need unique records based on multiple columns? Simply list them within the DISTINCT clause:

SELECT DISTINCT column1, column2, ...
FROM table_name;

A query like SELECT DISTINCT column1, column3 FROM table_name will yield unique combinations of values from column1 and column3, ignoring any duplicates in other columns.

The DISTINCT keyword provides a straightforward method for filtering and retrieving only unique data, ensuring data analysis is precise and efficient.

The above is the detailed content of How Can I Retrieve Only Unique Records from a SQL Table?. For more information, please follow other related articles on the PHP Chinese website!