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  • MySQL case when 使用

    case when 自定义排序时的使用
    根据 case when 新的 sort字段排序

        case 
        when t2.status = 4
        and t2.expire_time>UNIX_TIMESTAMP()
        and t2.expire_time<UNIX_TIMESTAMP(DATE_ADD(NOW(),INTERVAL 60 day)) then 4
            when `status` = 2  then 3
            when `status` = 3 then 2
            when t2.status = 4
            and t2.expire_time>UNIX_TIMESTAMP(DATE_ADD(NOW(),INTERVAL 60 day))
            and t2.expire_time<UNIX_TIMESTAMP(DATE_ADD(NOW(),INTERVAL 1 year)) then 1
        else 0
        end sort     
        
         $query->orderBy('sort desc ,t2.expire_time desc,t2.created_at desc');
        
    
    • 当colume 与condition 条件相等时结果为result
    case colume 
        when condition then result
        when condition then result
        when condition then result
    else result
    end
    

    image

    • 当满足某一条件时,执行某一result
    
    case  
        when condition then result
        when condition then result
        when condition then result
    else result
    end
    

    image

    • 当满足某一条件时,执行某一result,把该结果赋值到new_column_name 字段中
    case  
        when condition then result
        when condition then result
        when condition then result
    else result
    end new_column_name
    

    case when 用在select 语句中,新的字段new_column_name可以用来排序,但是不能用在where中

    image
    image
    end 后面加as new_colume_name
    image

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  • 原文地址:https://www.cnblogs.com/xp796/p/8042100.html
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