sql - 如何跨两个 SQL 表聚合计数？

Question

我有两张这样的桌子

Table 1: MedicineType  
MedicineTypeID MedicineTypeName
TE001         | HIV
TE002         | AIDS

Table 2: MsMedicine
MedicineID MedicineTypeID MedicineName
ME001     | TE001        | HIVgood 
ME002     | TE001        | HIVsmart
ME003     | TE002        | AIDSawesome

如何显示 MedicineTypeID、MedicineTypeName 和 MedicineCount（来自每个 MedicineType 上 MedicineID 的数量）示例：

MedicineTypeID MedicineTypeName MedicineCount
        TE001 | HIV            | 2
        TE002 | AIDS           | 1

Answer 1

Select mt.MedicineTypeID, mt.MedicineTypeName, Count(m.MedicineID) as MedicineCount
From MedicineType
Inner Join MSMedicine m On mt.MedicineTypeID = m.MedicineTypeID
Group By mt.MedicineTypeID, mt.MedicineTypeName

Answer 2

select MedicineTypeID,MedicineTypeName,count(*) as MedicineCount from MedicineType join MsMedicine on MedicineType.MedicineID=MsMedicine.MedicineID group by MedicineTypeID,MedicineTypeName