mysql - 当字段的计数为零时，如何通过聚合查询从组返回的值为零(0)？

Question

如果 Table.id 的计数为零，我想从类型查询中返回一个值(在本例中为零)。

 SELECT COUNT(Table1.id) AS AccountID, Table2.typeName AS Types
 FROM Table1
 LEFT JOIN Table3
 ON Table1.productID = Table3.productID
 LEFT JOIN Table2
 ON Table3.categoryID = Table2.CategoryID
 WHERE Table3.account_id = 51
 GROUP BY Table2.typeName;

This is the result that I would like to get

This is the result that I am currently getting

Table1
id      ProductID
1       1
1       1
2       2
2       1
1       1
id in this table 1 references categoryID in table2
---------------------------------------------------------

Table2
categoryID      typeName
1               SUV
2               BMW
3               Toyota
4               Audi
5               Suzuki
---------------------------------------------------------


Table3
categoryID      ProductID       account_id
2               1               51
1               2               52
3               1               51
categoryID is table3 references categoryID in table2
----------------------------------------------------------


My expected result should look like this

Count   Types
0       Toyota
0       Audi
0       Suzuki
3       SUV
2       BMW

我想计算表 1 中所有 ID 及其相应类型名称的数量。如果 id 不存在，我希望返回带有相应 typeName 的 0。

Answer 1

以下查询将起作用:

SELECT 
 COUNT(Table1.id) AS AccountID, 
 Table2.typeName  AS Types
 FROM Table2
 LEFT JOIN Table3
 ON Table3.categoryID = Table2.CategoryID
 AND Table3.account_id = 51
 LEFT JOIN Table1
 ON Table1.id = Table3.CategoryID     
 GROUP BY Table2.typeName;

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