Why does distinct and group by not work?
Usually, GROUP BY can solve this, but it might not be the most efficient method, or fail to accomplish other issues with the requirements in the query. The good method to solve the problem is to step back, and look at both the data and the requested output, which, once clarified, can be translated into SQL Query “easily”.
Is the result of group by distinct queries the same?
While Adam Machanic is correct when he says that these queries are semantically different, the result is the same – we get the same number of rows, containing exactly the same results, and we did it with far fewer reads and CPU.
How to eliminate duplicates in a query using distinct?
Often, when running a query with joins, the results show up “duplicates”, and often, those duplicates can be “eliminated” in the results using DISTINCT, for example. Using DISTINCT is simple: just add it after the SELECT keyword, and you don’t get duplicates.
When to use group by to remove duplicates?
GROUP BY does not “remove duplicates”. GROUP BY allows for aggregation. If all you want is to combine duplicated rows, use SELECT DISTINCT. If you need to combine rows that are duplicate in some columns, use GROUP BY but you need to to specify what to do with the other columns.
Why is distinct not working in SQL query?
DISTINCT should be thought of as a clause, rather than a function to which you pass a column name as an argument. It returns the set of distinct rows over the superset returned by the query, rather than distinct values in a single column. The issue may be your use of paranthesis in the distinct call. Try just:
When to use distinct with or without parentheses?
Using DISTINCT without parentheses should get you what you want. DISTINCT should be thought of as a clause, rather than a function to which you pass a column name as an argument. It returns the set of distinct rows over the superset returned by the query, rather than distinct values in a single column.
What does select distinct do in Microsoft Excel?
SELECT DISTINCT is a “row operator”, not a function, and not magic. It will evaluate ALL of the columns that you have listed and remove rows that have exactly the same values in all columns so that each row returned is different to every other row that is returned.