David Rowley 为string_agg()和array_agg()函数实现了并行聚合的新功能。该补丁由 Andres Freund、Tomas Vondra、Stephen Frost 和 Tom Lane 审核。由David Rowley提交。提交消息是: This addscombine, serial and deserial functions for the array_agg() and string_agg()aggregate functions, thus allowing these...
聚合函数(aggregate function)针对一组数据行进行运算,并且返回一条结果。PostgreSQL 支持以下常见的聚合函数: AVG- 计算一组值的平均值 COUNT- 统计一组值的数量 MAX- 计算一组值的最大值 MIN- 计算一组值的最小值 SUM- 计算一组值的和值 STRING_AGG- 连接一组字符串 以下示例分别返回了 IT 部门所有员工的...
string_agg,array_agg 这两个函数的功能大同小异,只不过合并数据的类型不同。 https://www.postgresql.org/docs/9.6/static/functions-aggregate.html array_agg(expression) AI代码助手复制代码 把表达式变成一个数组 一般配合 array_to_string() 函数使用 string_agg(expression, delimiter) AI代码助手复制代码 直...
Here’s some examples of some of the general-purpose aggregation functions: >>> TestModel.objects.aggregate(result=StringAgg('field1', delimiter=';')) {'result': 'foo;bar;test'} >>> TestModel.objects.aggregate(result=ArrayAgg('field2')) {'result': [1, 2, 3]} >>> TestModel.objec...
David Rowley 为string_agg()和array_agg()函数实现了并行聚合的新功能。该补丁由Andres Freund、Tomas Vondra、Stephen Frost 和 Tom Lane 审核。由David Rowley提交。提交消息是:This addscombine, serial and deserial functions for the array_agg() andstring_agg()aggregate functions, thus allowing these agg...
1SELECT2user_id,3STRING_AGG(event,','ORDER BYevent_dateDESC)ASrecent_events4FROM5user_events6GROUP BY7user_id; 4.2 Nested Aggregations For more intricate queries, combineSTRING_AGG()with other aggregation functions: Copy 1SELECT2department,3STRING_AGG(employee_name,',')ASemployee_list,4AVG(...
PostgreSQL Tutorial/PostgreSQL Aggregate Functions PostgreSQL Aggregate Functions Summary: in this tutorial, you will learn how to use the PostgreSQL aggregate functions such as AVG(), COUNT(), MIN(), MAX(), and SUM(). Introduction to PostgreSQL aggregate functions Aggregate functions perform a calc...
string_agg,array_agg 这两个函数的功能大同小异,只不过合并数据的类型不同。 https://www.postgresql.org/docs/9.6/static/functions-aggregate.html array_agg(expression) 把表达式变成一个数组 一般配合 array_to_string() 函数使用 1. 2. 1 2
Aggregate functions are used to produce summarized results. They operate on sets of rows. They return results based on groups of rows. By default, all rows in a table are treated as one group. The GROUP BY clause of the select statement is used to divide rows into smaller groups. ...
PostgreSQL Aggregate Functions Date Functions JSON Functions Math Functions String Functions Window Functions API PostgreSQL C# PostgreSQL PHP PostgreSQL Python PostgreSQL JDBC Back to Docs Neon PostgreSQL Tutorial Search Home Getting Started Administration Adva...