mysql - MySQL SELECT結果セットにカスタムカウントを含めるにはどうすればよいですか？

Question

次の2つのテーブルがあります。

TABLE: area
*City_ID   *Number   Name
--------   -------   ----
SUR        1         Fleetwood
SUR        2         Whalley
SUR        3         Guildford
SUR        4         Newton
SUR        5         Cloverdale
SUR        6         South Surrey
ABB        1         Abbotsford East
ABB        2         Abbotsford West
ABB        3         Aberdeen
ABB        4         Bradner
ABB        5         Central Abbotsford
ABB        6         Matsqui
ABB        7         Poplar
ABB        8         Sumas Mountain
ABB        9         Sumas Prairie

TABLE: city
*ID        Name
---        ----
SUR        Surrey
ABB        Abbotsford
LAN        Langley

次のステートメントを使用します。

SELECT DISTINCT area.City_ID, city.Name
FROM area
INNER JOIN city
WHERE area.City_ID = city.ID

私は得る：

SELECT:
City_ID    city.Name
-------    ---------
SUR        Surrey
ABB        Abbotsford

しかし、どうすれば次を選択できますか？

SELECT:
City_ID    city.Name    area_COUNT
-------    ---------    ----------
SUR        Surrey       6
ABB        Abbotsford   9

対応するarea_COUNT各行の行数はどこにありますか？areaCity_ID

Answer 1

GROUP BYの代わりに使用DISTINCT:

SELECT city.City_ID, city.Name, COUNT(*)
FROM area
INNER JOIN city
WHERE area.City_ID = city.ID
GROUP BY city.ID

Answer 2

Groupby句にNameも追加する必要があります

SELECT area.City_ID, city.Name, count(*) as area_COUNT 
FROM area 
INNER JOIN city 
WHERE area.City_ID = city.ID 
GROUP BY area.City_ID,City.Name

Answer 3

DISTINCT の代わりに GROUP BY を使用します。

SELECT city.City_ID, city.Name, COUNT(*) FROM area INNER JOIN city WHERE area.City_ID = city.ID GROUP BY city.ID

Answer 4

末尾に group by を追加

SELECT area.City_ID, city.Name, count(*) as area_COUNT
FROM area
INNER JOIN city
WHERE area.City_ID = city.ID
GROUP BY area.City_ID