How to get values from list and put it in where condition

I have datagridview have check boxes checked

but my problem how to update checked box values from datagridview in database .

button1_click event

	{  

	        string subjId;  

	        List<string> lines = new List<string>();  

	        for (int i = 0; i < gvSubjectsList.Rows.Count; i++)  

	        {  

	       bool Ischecked =Convert.ToBoolean(gvSubjectsList.Rows[i].Cells["Select"].Value);   

	            if (Ischecked == true)  

	            {  

	                subjId = gvSubjectsList.Rows[i].Cells["SubjectId"].Value.ToString();  

	                lines.Add(subjId);  

	            }  

	    }

	   //update courses set courseStatus = true where subjId found in lines

	 

	    }

my problem how to

//update courses set courseStatus = true where subjId found in lines

How to write query select in c# to get what numbers found in list ?

update courses set courseStatus = true where ??????

what i write in place of ?????????

thanks