mysql - 在图表中添加零值

Question

我构建了以下查询：

SELECT GVA14.COD_ZONA, Sum(GVA12.IMPORTE) AS SumOfIMPORTE
FROM GVA14 LEFT JOIN GVA12 
  ON GVA14.COD_CLIENT = GVA12.COD_CLIENT
WHERE Month(GVA12.FECHA_EMIS)=Month(curdate())
AND Year(GVA12.FECHA_EMIS)=Year(curdate())
GROUP BY GVA14.COD_ZONA;

COD_ZONA但是我想显示的还有其他值。如果我去掉月份和年份过滤器，这些就在那里。这是任何有兴趣的人的SQL Fiddle。http://sqlfiddle.com/#!2/3aae1/3

---

编辑1#

我现在有以下查询：

SELECT GVA14.COD_ZONA, Coalesce(Sum(GVA12.IMPORTE), 0) AS SumOfIMPORTE
FROM GVA14 
LEFT JOIN GVA12 
  ON GVA14.COD_CLIENT = GVA12.COD_CLIENT
  AND Month(GVA12.FECHA_EMIS)=Month(curdate())
  AND Year(GVA12.FECHA_EMIS)=Year(curdate())
GROUP BY GVA14.COD_ZONA;

但是当我尝试执行它时，大约需要 110 秒，并且在此之前我需要它的程序超时。我根据@Bluefeet 的建议创建了一个索引，并将其命名为 Zones，并将 GVA14.COD_ZONA 包含在其中。

接下来我该怎么做？

Answer 1

将WHERE子句上的过滤器移至JOIN条件。如果您将过滤器留在WHERE子句中，则查询的作用类似于 anINNER JOIN而不是 a LEFT JOIN：

SELECT GVA14.COD_ZONA, Coalesce(Sum(GVA12.IMPORTE), 0) AS SumOfIMPORTE
FROM GVA14 
LEFT JOIN GVA12 
  ON GVA14.COD_CLIENT = GVA12.COD_CLIENT
  AND Month(GVA12.FECHA_EMIS)=Month(curdate())
  AND Year(GVA12.FECHA_EMIS)=Year(curdate())
GROUP BY GVA14.COD_ZONA;

请参阅带有演示的 SQL Fiddle

结果：

| COD_ZONA | SUMOFIMPORTE |
---------------------------
|       01 |         3000 |
|       02 |         1000 |
|       03 |            0 |

Answer 2

我已经通过在表上添加 4 个索引（不知道这是否太多！）来解决这个问题。有效...

Answer 3

    SELECT GVA14.COD_ZONA
         , COALESCE(Sum(GVA12.IMPORTE),0) AS SumOfIMPORTE
      FROM GVA14 
      LEFT 
      JOIN GVA12 
        ON GVA14.COD_CLIENT = GVA12.COD_CLIENT
       AND Month(GVA12.FECHA_EMIS)=Month(curdate())
       AND Year(GVA12.FECHA_EMIS)=Year(curdate())
     GROUP 
        BY GVA14.COD_ZONA;