Question

当我在create view构造中使用此代码时，它返回空结果集。我尝试在案例后使用列名并删除行中的列名...没有变化......任何想法。我已经确定问题是在案例陈述中通过评论并运行它并且它工作正常....

DROP TABLE IF EXISTS `duplicaterecords`;

CREATE TABLE `duplicaterecords` (
  `RRID` int(11) DEFAULT NULL,
  `duplicateInfo` varchar(200) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

INSERT INTO `duplicaterecords` (`RRID`, `duplicateInfo`)
VALUES
    (3920011,'Repeated:12009:CLEAR'),
    (3920011,'Repeated:12012:CLEAR'),
    (4233901,'Repeated:18129:HIT'),
    (4820129,'Repeated:22901:PENDING'),
    (4820129,'Repeated:22983:PENDING'),
    (4233901,'Duplicate:5555555:CLEAR');

    select grouped.*
, base.duplicateInfo 
from 
( 
    select grouped.RRID, max(grouped.duplicateInfoId) duplicateInfoId
    from (
        select RRID
        , cast(substring_index(substring_index(duplicateInfo,':',2 ),':',-1) as unsigned) duplicateInfoId
        , duplicateInfo 
        from duplicateRecords  
    ) grouped
    group by grouped.RRID
) grouped
inner join (
    select RRID
    , cast(substring_index(substring_index(duplicateInfo,':',2 ),':',-1) as unsigned) duplicateInfoId
    , duplicateInfo 
    from duplicateRecords  
) base
on grouped.duplicateInfoId = base.duplicateInfoId ;

-- example results

RRID    duplicateInfoId duplicateInfo
3920011 12012   Repeated:12012:CLEAR
4233901 5555555 Duplicate:5555555:CLEAR
4820129 22983   Repeated:22983:PENDING

Answer 1

就像这个例子一样：

尝试运行此

 set @fulfillStatus = 1;
    select 
    CASE 
        when @fulfillStatus = 0 then 'open'
        when @fulfillStatus = 1 then 'processing'
        when @fulfillStatus = 2 then 'complete'
        when @fulfillStatus = 5 then 'Shipped'
        when @fulfillStatus = 9 then 'void'
    else "None"
    END as "Order Status"

MySql case语句错误

1 个答案: