MySQL where子句带有条件以显示特定年龄

Question

所有Mysql查询似乎都可以正常工作，并且期望表中的“年龄”满足条件。 例如，我需要年龄来过滤此条件，使其从age >=20到age <=30 ，外翻似乎有效，但年龄不起作用。

例如在这里检查链接

$sql = "SELECT * FROM  `file_records` 
           WHERE  (`country` = '$country' OR '$country' IS NULL) 
               OR (`gender` = '$gender' OR'$gender' IS NULL) 
               OR (`cast` = '$cast' OR '$cast' IS NULL) 
               OR (
                   (`age` >= '$age_from' OR   '$age_from' IS NULL) 
                     AND (`age` <= '$age_to' OR '$age_to' IS NULL)
                  ) 
           LIMIT 0 , 30";

Answer 1

您可以像这样使用mysql BETWEEN函数

age BETWEEN 20 AND 30

Answer 2

您正在检查> =的日期和日期。

$sql = "SELECT * FROM  `file_records` 
         WHERE (`country` = '$country' OR '$country' IS NULL) 
           OR (`gender` = '$gender' OR' $gender' IS NULL) 
           OR (`cast` = '$cast' OR '$cast' IS NULL) 
           OR ((`age` >= '$age_from' OR '$age_from' IS NULL) 
                AND (`age` <= '$age_to' OR '$age_to' IS NULL)) 
         LIMIT 0 , 30";

Answer 3

您可以在和运算符之间选择年龄，例如这种格式

SELECT column_name(s)
FROM table_name
WHERE age
BETWEEN age >=20 and age <=30

Answer 4

如果您echo $sql; ，您会看到'' IS NULL不可能的。

你想要类似的东西

OR ((`age` >= '$age_from' OR '$age_from' = '') 
            AND (`age` <= '$age_to' OR '$age_to' = ''))