请问这个sql应该怎么写，mysql数据库

Question

我现在有两张表A和B，其中表A的主键在B中是外键，我现在要查询A中每个主键在B中的个数外加A表的所有数据，请问这种怎么写？

Answer 1

SELECT
    G.count,A.*
FROM
    (
        SELECT
            COUNT(*) AS count,
            Id
        FROM
            B
        GROUP BY
            Id
    ) G
JOIN A ON G.Id = A.Id;

Answer 2

不建议使用关联查询，sql分开写。易于维护。

Answer 3

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