Hello :

If I want to save the text of( textbox1) to entry inside a table(in access data base),every time I write texts it must write it to the DB,,in the next times if I enter in textbox1.text a text it's exist in database,,a message box error must appear(I mean inside dataBase there are no duplicated values)....any idea please???
Thanks in advance..

Use a SQL stored procedure for the data integrity part of your task. Use an OUT parameter to indicate a successful write, or duplicate. Base your program logic on the OUT parameter.