从字符串向 datetime 转换时失败。如何解决

declare @MonthsWage datetime
set @MonthsWage='2012-07-01'
declare @JiangXiangJinE  nvarchar(max)
select @JiangXiangJinE=coalesce(@JiangXiangJinE + ',' , 'update wage set ')  + en+'=b.'+en  from SystemDict where TableName='Awards'
set @JiangXiangJinE=@JiangXiangJinE+' from AwardsAmountSetting b where wage.PostID=b.PostID and MonthWage='''+@MonthsWage+''''
print @JiangXiangJinE

--提示
Msg 241, Level 16, State 1, Line 2
从字符串向 datetime 转换时失败。

declare @MonthsWage datetime
set @MonthsWage='2012-07-01'
print @MonthsWage 
--这样输出的结果是：07  1 2012 12:00AM

------解决方案--------------------
declare @MonthsWage datetime
set @MonthsWage='2012-07-01'
declare @JiangXiangJinE  nvarchar(max)
select @JiangXiangJinE=coalesce(@JiangXiangJinE + ',' , 'update wage set ')  + en+'=b.'+en  from SystemDict where TableName='Awards'
set @JiangXiangJinE=@JiangXiangJinE+' from AwardsAmountSetting b where wage.PostID=b.PostID and  
MonthWage='''convert(varchar(10),@MonthsWage,120)'''' --这里修改不行？  
print @JiangXiangJinE
-->那你这个MonthWage字段是什么类型，字段值是什么样的
-->确认是否是这句出现错误
-->如果不能确认，给出表结构和错误附近的代码

------解决方案--------------------
declare @MonthsWage datetime
set @MonthsWage='2012-07-01'
declare @JiangXiangJinE  nvarchar(max)
select @JiangXiangJinE=coalesce(@JiangXiangJinE + ',' , 'update wage set ')  + en+'=b.'+en  from SystemDict where TableName='Awards'
set @JiangXiangJinE=@JiangXiangJinE+' from AwardsAmountSetting b where wage.PostID=b.PostID and convert(varchar(10),MonthWage,21)='''+cast(@MonthsWage as varchar)+''''
print @JiangXiangJinE