I now have two tables An and B, in which the primary key of table An is a foreign key in B. now I want to query the number of each primary key in A plus all the data in table A. how do you write this?
I now have two tables An and B, in which the primary key of table An is a foreign key in B. now I want to query the number of each primary key in A plus all the data in table A. how do you write this?
SELECT
G.count,A.*
FROM
(
SELECT
COUNT(*) AS count,
Id
FROM
B
GROUP BY
Id
) G
JOIN A ON G.Id = A.Id;is not recommended to use associated queries. Sql is written separately. Easy to maintain.
SELECT COUNT (og. order_id ) AS num,o.* FROM va_order o LEFT JOIN va_order_goods og ON o. order_id = og. order_id GROUP BY o. order_id
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