子查询和连接 SQL

Question

我想知道哪个制造商的车辆销量最高 这会产生 2 个或更多产品点。并显示制造商名称和总数 制造商的车辆所涉及的销售量。

CREATE TABLE product (
    prod_code          NUMBER(3) NOT NULL,
    prod_description   VARCHAR2(75) NOT NULL,
    prod_points        NUMBER(2) NOT NULL
);

CREATE TABLE product_sale (
        sale_no         NUMBER(8) NOT NULL,
        sale_datetime   DATE NOT NULL,
        sale_location   VARCHAR2(100) NOT NULL,
        prod_code       NUMBER(3) NOT NULL,
        officer_id     NUMBER(8) NOT NULL,
        lic_no   CHAR(10) NOT NULL,
        veh_no  CHAR(17) NOT NULL
    );

CREATE TABLE vehicle (
    veh_no         CHAR(17) NOT NULL,
    veh_manufyr     DATE NOT NULL,
    veh_maincolor   VARCHAR2(20) NOT NULL,
    veh_manufname   VARCHAR2(30) NOT NULL,
    veh_modname     VARCHAR2(20) NOT NULL,
    veh_type        CHAR(2) NOT NULL
);

我不确定如何关联 3 个不同的连接并找到输出。

预期输出：

Answer 1

类似的东西？ （未测试）

SELECT veh_manufname, total_sales_count
FROM (
   SELECT v.veh_manufname, 
          count(*) as total_sales_count,
          count( CASE WHEN prod_code IN (
                     SELECT prod_code FROM product WHERE prod_points >= 2
                ) THEN 1 END ) as sales_point_2
   FROM product_sale p
   JOIN vehicle v ON v.veh_no = p.veh_no
   GROUP BY v.veh_manufname
)
ORDER BY sales_point_2 DESC
LIMIT 1
-- LIMIT 1 works on most databases: MySql, PostgreSql, SQLite ....
-- If you are using ORACLE then remove the above line and uncomment the below one
-- FETCH 1 ROWS ONLY

-- If you are using SQL Server then (probably) SELECT TOP 1 will work but I'am not sure