本文将详细介绍 DISTINCT 和 GROUP BY 的区别、适用场景以及它们对查询性能的影响。 在 SQL 查询中，DISTINCT 和 GROUP BY 是两个常见的用于去重和分组的操作符。然而，尽管它们在某些情况下可以达到相同的效果，但它们在原理、适用场景和性能方面却有很大的不同。

在大多数例子中，DISTINCT可以被看作是特殊的GROUP BY，它们的实现都基于分组操作，且都可以通过松散索引扫描、紧凑索引扫描(关于索引扫描的内容会在其他文章中详细介绍，就不在此细致介绍了)来实现。 DISTINCT和GROUP BY都是可以使用索引进行扫描搜索的。

….sql Summary: This revision adds yb_pg_select_distinct.sql which is based on select_distinct.sql yb_pg_select_distinct_on.sql is added based on select_distinct_on.sql The newly added file would be ...

Do you want to find out how to avoid duplicates in the results of a SQL SELECT query? This article will show you how. Simply use the DISTINCT clause and between the SELECT clause and the fields.

As we all might know that selecting all records from the database in cakephp can be done using the find("all") method, But there are chances of duplicate records may ...

After #9114, the IT engine fails to run well with the SELECT DISTINCT SQL. It is necessary to find the cause and fix it.