DISTINCT ON ( expression [, ...] ) keeps only the first row of each set of rows where the given expressions evaluate to equal. [...] Note that ... ... <看更多>

A brief beginner's introduction to the DISTINCT operator in SQL. DISTINCT creates a set of unique records ... ... <看更多>

It does not send any column to display. You dont do distinct on any columns; It is just a keyword added at the beginning of the select statement ... ... <看更多>

You probably don't want to hear this, but the best option to speed up SELECT DISTINCT is to avoid DISTINCT to begin with. In many cases (not all!) it can be ... ... <看更多>

用传统SQL当然有办法解决，但是都不够优雅，PostgreSQL的SQL扩展语法Distinct ON能一步到位解决这一类问题。 DISTINCT ON 语法. SELECT DISTINCT ON (expression [, ... ... <看更多>

Returns a copy of the relation with a SQL DISTINCT clause. Overloads: #distinct(*columns) ⇒ Relation. Create a distinct statement from column names. ... <看更多>