SQL CASE查询返回复选框的额外记录

Question

当复选框Period Type为陈词滥调时，查询返回1。没有点击它是0。期间类型属性只能存储NULL或当前帐户期间。 我需要为BIT = 1或0

过滤这些突出显示的行

(
CASE 
    WHEN Period.CheckBoxPeriodType = 1 THEN 
        CASE
            WHEN (Post.ColumnNumber = Thread.ColumnNumber 
                    AND LEN(Thread.AccountPeriodType) > 0 AND  Thread.AccountPeriodType <> '')
                    AND Post.PeriodType = Thread.PeriodType 
            THEN Thread.AccountPeriodType               
            ELSE NULL           
        END
            WHEN Post.CheckBoxPeriodType = 0 AND  THEN ''
            WHEN Post.CheckBoxPeriodType IS NULL THEN cellFormat.AccountPeriodType      

        END  
     ) as MyCaseStatement