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＆＃39;宠物＆＃39;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

如何连接字符串并以它给出的方式输出字符串＆＃34; Ron Weasley有X个宠物＆＃34; （其中X = 2）？

对于X = 2部分我知道'select count(name) from pets where owner = 'Ron Weasley';'但不确定如何在PSQL中连接和输出字符串。

Answer 1

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