PSQL：字符串连接和输出字符串

Question

我是psql的新手。 我有一张桌子“宠物”如下。

name  | species |  owner  | gender |  color 
-------------+---------+--------------------+--------+--------------- 
Nagini  | snake | Lord Voldemort  | female | green 
Hedwig  | owl  | Harry Potter  | female | snow white 
Scabbers | rat  | Ron Weasley  | male | unspecified 
Pigwidgeon | owl  | Ron Weasley  | male | grey 
Crookshanks | cat  | Herminone Granger | male | ginger 
Mrs Norris | cat  | Argus Filch  | female | dust-coloured 
Trevor  | toad | Neville Longbottom | male | brown 

我如何连接字符串和输出的方式字符串，它赋予“罗恩·韦斯莱有X的宠物”（其中X = 2）？

我知道'select count(name) from pets where owner = 'Ron Weasley';'为X = 2部分，但不知道如何在PSQL中连接并输出字符串。

Answer 1

SELECT p.owner||' has ' count(p.name)||' pets' as conc_output 
    FROM pets p 
WHERE owner = 'Ron Weasley';