Hello everyone, I have a datagridview like the left column is the meeting room I took from the database and the hour column from 08:00 to 18:00 is that I add a new column in the datagridviewcolumn and I set Name="column1", Headertext="08: 00" to..... end of....Name="column18, Headertext="18:00" after selecting the start time, end time and room, it will be displayed on the grid as shown. but I don't know how to compare the input time and then compare it with the value of that headertext, hope someone can guide me