SQL 语法错误分析：LEFT JOIN 和 COUNT 函数使用错误

SELECT t1.name, t1.riqi, COUNT(DISTINCT t1.app) AS "用现金买了多少种商品", COUNT(t1.app) AS "用现金买多少个商品", COUNT(DISTINCT t1.app) AS "累计买多少种商品", COUNT(t1.app) AS "累计个商品" FROM TEST2 AS t1 LEFT JOIN TEST2 AS t2 ON t1.name = t2.name AND t1.riqi >= t2.RIQI WHERE t1.pay = '1' GROUP BY t1.name, t1.riqi; 该查询语句中存在两个语法错误： 1. 在 COUNT(DISTINCT t2.app) AS 累计买多少种商品, COUNT(t2.app) AS 累计个商品 这两行中，t2.app 是在 JOIN 子句中引用的，应该在 SELECT 子句中用 t1.app 代替。 2. 在 JOIN 子句中，t1 和 t2 之间的条件应该用 ON 关键字连接，而不是用 WHERE 关键字。 正确的 SQL 查询语句应该是： SELECT t1.name, t1.riqi, COUNT(DISTINCT t1.app) AS "用现金买了多少种商品", COUNT(t1.app) AS "用现金买多少个商品", COUNT(DISTINCT t1.app) AS "累计买多少种商品", COUNT(t1.app) AS "累计个商品" FROM TEST2 AS t1 LEFT JOIN TEST2 AS t2 ON t1.name = t2.name AND t1.riqi >= t2.RIQI WHERE t1.pay = '1' GROUP BY t1.name, t1.riqi;