MySQL：对自定义生成的列（别名）进行 IS NOT NULL 检查答案

【问题标题】：MySQL : IS NOT NULL check on custom generated column(alias)MySQL：对自定义生成的列（别名）进行 IS NOT NULL 检查
【发布时间】：2015-07-24 06:25:06
【问题描述】：

存储过程到目前为止工作正常，但我想要记录仅在 dist_calculated IS NOT NULL 时。当我在 where clause 中使用该条件时，它显示错误 #1054 - Unknown column 'dist_calculated' in 'where clause'。如果没有 where 子句，它运行良好并且返回 NULL 记录也像：

entity_id   dist_calculated     
49              NULL
50              NULL
52              4460.615
51              4875.179

我想排除 NULL。

我试过WHERE dist_calculated IS NOT NULL 和WHERE cpe.dist_calculated IS NOT NULL 仍然报错。

我的存储过程是：

DELIMITER //
CREATE PROCEDURE get_close_childcares(IN latUser DECIMAL(15,6),IN lngUser DECIMAL(15,6) )
BEGIN
    /*Get 4 ids of closest childcares*/
    /*Outer query   
    @param : userLat, userLng, Current childcare lat,current childcare lng
    Note : Inner query returns lat , lng of Current product 176 : lat , 177: lng
    */
    SELECT cpe.entity_id , get_distance_in_miles_between_geo_locations(latUser,lngUser,
        (SELECT cpev.value FROM catalog_product_entity_varchar AS cpev 
            WHERE (cpev.entity_id = cpe.entity_id AND cpev.attribute_id = 176)
        ),
        (SELECT cpev.value FROM catalog_product_entity_varchar AS cpev 
            WHERE (cpev.entity_id = cpe.entity_id AND cpev.attribute_id = 177)
        )
    ) AS dist_calculated
    FROM catalog_product_entity AS cpe
    WHERE dist_calculated IS NOT NULL
    ORDER BY dist_calculated ASC
    LIMIT 0,4;

END
//
DELIMITER ;

并调用存储过程：

call get_close_childcares(19.992100,73.777000)

谢谢。

【问题讨论】：

标签： mysql stored-procedures where alias notnull

【解决方案1】：

MySQL 确实允许在 GROUP BY 和 HAVING 上使用列别名，但不允许在 WHERE 语句中使用。因此，您需要在 WHERE 中使用完整的定义，例如

SELECT cpe.entity_id , get_distance_in_miles_between_geo_locations(latUser,lngUser,
    (SELECT cpev.value FROM catalog_product_entity_varchar AS cpev 
        WHERE (cpev.entity_id = cpe.entity_id AND cpev.attribute_id = 176)
    ),
    (SELECT cpev.value FROM catalog_product_entity_varchar AS cpev 
        WHERE (cpev.entity_id = cpe.entity_id AND cpev.attribute_id = 177)
    )
) AS dist_calculated
FROM catalog_product_entity AS cpe
WHERE
get_distance_in_miles_between_geo_locations(latUser,lngUser,
        (SELECT cpev.value FROM catalog_product_entity_varchar AS cpev 
            WHERE (cpev.entity_id = cpe.entity_id AND cpev.attribute_id = 176)
        ),
        (SELECT cpev.value FROM catalog_product_entity_varchar AS cpev 
            WHERE (cpev.entity_id = cpe.entity_id AND cpev.attribute_id = 177)
        )
    ) IS NOT NULL
ORDER BY dist_calculated ASC
LIMIT 0,4;

【讨论】：

你能告诉我what could be done here then 吗？

【解决方案2】：

你可以试试这个伙伴：

SELECT
    cpe.entity_id,
    get_distance_in_miles_between_geo_locations (
        latUser,
        lngUser,
        cpev_1.`value`,
        cpev_2.`value`
    ) AS dist_calculated
FROM
    catalog_product_entity cpe
    INNER JOIN catalog_product_entity_varchar cpev_1 ON cpev_1.entity_id = cpe.entity_id
        AND cpev_1.attribute_id = 176
    INNER JOIN catalog_product_entity_varchar cpev_2 ON cpev_2.entity_id = cpev.entity_id
        AND cpev_2.attribute_id = 177
ORDER BY
    dist_calculated ASC
LIMIT 0,4;

【讨论】：

【解决方案3】：

请尝试

CREATE PROCEDURE get_close_childcares(IN latUser DECIMAL(15,6),IN lngUser DECIMAL(15,6) )
BEGIN
    /*Get 4 ids of closest childcares*/
    /*Outer query   
    @param : userLat, userLng, Current childcare lat,current childcare lng
    Note : Inner query returns lat , lng of Current product 176 : lat , 177: lng
    */
    SELECT cpe.entity_id , get_distance_in_miles_between_geo_locations(latUser,lngUser,
        (SELECT cpev.value FROM catalog_product_entity_varchar AS cpev 
            WHERE (cpev.entity_id = cpe.entity_id AND cpev.attribute_id = 176)
        ),
        (SELECT cpev.value FROM catalog_product_entity_varchar AS cpev 
            WHERE (cpev.entity_id = cpe.entity_id AND cpev.attribute_id = 177)
        )
    ) AS dist_calculated
    FROM catalog_product_entity AS cpe
    WHERE get_distance_in_miles_between_geo_locations(latUser,lngUser,
        (SELECT cpev.value FROM catalog_product_entity_varchar AS cpev 
            WHERE (cpev.entity_id = cpe.entity_id AND cpev.attribute_id = 176)
        ),
        (SELECT cpev.value FROM catalog_product_entity_varchar AS cpev 
            WHERE (cpev.entity_id = cpe.entity_id AND cpev.attribute_id = 177)
        )
    ) IS NOT NULL
    ORDER BY dist_calculated ASC
    LIMIT 0,4;

END

【讨论】：

不工作，为其生成存储过程会出错