mysql-C#Mysqldatagridview控件列标题中文乱码问题

用C#从Mysql中读取数据到datagridview控件中，结果列标题中文乱码，内容没事。代码如下：
string commstr = "SELECT Patient_ID as ID,NAME as 姓名,TARGET as 患侧,DIAGNOSIS as 诊断 FROM PatientInfo";
this.data_case.DataSource = DBOperate.DBOperate.selectData(commstr, 数据库.DBConnection.SqlConnstr);
int rows = this.data_case.RowCount - 1;
for (int i = 0; i < rows; i++)
{
if (this.data_case.Rows[i].Cells[2].Value.ToString() == "L")
this.data_case.Rows[i].Cells[2].Value = "左手";
else
this.data_case.Rows[i].Cells[2].Value = "右手";
}
列标题名称本来应该是ID 姓名 患侧 诊断 的，但出现了中文乱码。我在DOS下对MySQL进行数据库查询操作，同样查询命令"SELECT Patient_ID as ID,NAME as 姓名,TARGET as 患侧,DIAGNOSIS as 诊断 FROM PatientInfo"的标题是ID 姓名 患侧 诊断，没有乱码。这是哪里出了问题，要怎么解决呢？