How to Get Unique Records in SQL Using DISTINCT?

Extracting Unique Data from SQL Tables

Working with large databases often involves dealing with duplicate entries. To efficiently retrieve only unique records, SQL offers the DISTINCT keyword. This powerful function ensures you only receive one instance of each unique value combination.

For instance, if your table contains duplicate values in a column named "column2", you can use the following SQL query to obtain only the unique entries:

SELECT DISTINCT column2, column3, ...
FROM table_name;

The DISTINCT keyword, placed before the column names, instructs SQL to filter out duplicates, returning only the first occurrence of each unique combination of specified column values.

Let's consider a practical example. Given a table with redundant data, the query below will isolate unique records:

SELECT DISTINCT item1, data1
FROM table_name;

This would yield a table resembling:

<code>╔══════════╦═════════╗
║   item1   ║   data1  ║
╠══════════╬═════════╣
║ item1     ║ data1    ║
║ item2     ║ data3    ║
║ item3     ║ data4    ║
╚══════════╩═════════╝</code>

Observe that the duplicate "item1" entry has been eliminated, leaving only unique rows based on the specified columns. This demonstrates the effectiveness of DISTINCT in retrieving clean, unique datasets from your SQL database.

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