PostgreSQL: String summation (concatenation)

Solution:

1. Convert table to array

2. Splice the array with array_to_string

Example:

--Create a test tableDROP TABLE IF EXISTStest;CREATE TEMP TABLETest ("Id"int, "Name"varchar( -), "Type"int);INSERT  intoTest ("Id", "Name", "Type")VALUES(1,'NO1',1),(2,'NO2',2),(3,'NO3',2),(4,'NO4',2),(5,'NO5',3),(6,'NO6',3);--convert results to arrays--Select Array (select "Name" from Test)--merging arrays into strings--Select Array_to_string (array[1,2,3], ', ')--results after merging--Select array_to_string (Array (select "Name" from Test), ', ')SELECT"Type", (array_to_string (Array (SELECT"Name" fromTest asTWHERET. " Type "=Test. " Type "),',') ) fromTestGROUP  by"Type";

DROP TABLE test;

PostgreSQL: String summation (concatenation)