从字符串中获取数据字符串整型数据类型

Question

我想从日期和时间获取总和（成本）的数据。我的表字段的数据类型是id是INT AUTO INCREMENT，dd是varchar，mm是varchar，yyyy varchar和dd值是01到31，mm值是01到12，年值是4位数年份（2016或2015 ... ） 正是我想要总和（成本）= 143

SELECT SUM(cost) FROM costing 
WHERE 
    ((dd> CAST('05' AS SIGNED) AND mm= CAST('12' AS SIGNED) AND yyyy= CAST('2015' AS SIGNED)) 
    AND 
    ((dd<= CAST('23' AS SIGNED) AND mm = CAST('01' AS SIGNED) AND yyyy= CAST('2016' AS SIGNED))) 

    order by id 

Answer 1

您可以使用CAST AS DATE函数是这样的：

SELECT 
    SUM(cost) FROM costing 
WHERE 
    CAST(CONCAT(yyyy,mm,dd) AS DATE) BETWEEN '2015-12-05' AND '2016-01-23' 

Answer 2

首先，你应该考虑你的数据类型。日期不应以varchar或整数数据类型。请参考此http://www.w3schools.com/sql/sql_datatypes.asp

然后你可以使用之间。请参考此http://www.w3schools.com/sql/sql_between.asp

然后，您在您的查询中不需要order by id。

您的查询会喜欢 SELECT SUM(cost) FROM costing WHERE costingdate BETWEEN "5-12-2015" AND 23-1-2015"