c How to read out the numbers in the textbook and assign values to the variables you define

It's textbox, right? textbook?

double somedouble;

if(!,out somedouble)

Make a mistake. return;

Here you can use the somedouble that was successfully converted.

1. There are no errors in all the syntax, that is, the SQL statement is somewhat unprofessional.

It is best to use such as; In addition, in parentheses, " should be used'Finally, you should judge whether the data is inserted successfully.

sqlconnection con = new sqlconnection("server=;user id=sa;password=sa;database=students");

Look at you. Either there is a problem with the IP address, or the password for this SA account is incorrect. You can try it again.

You can't see anything wrong with this paragraph.,You have to debug it to see which step went wrong.,And then send the error** out to see.。。。

Then you must not have logged in, and the SA user password is incorrect.

There are no errors in the syntax, but the SQL statement is somewhat unprofessional.

It is best to use such as; In addition, in parentheses, " should be used'Finally, you should judge whether the data is inserted successfully.

The argument is in the constructor, and the load method cannot pass the argument.

private void click(object sender, eventargs e).

data source=;initial catalog=testdb;connect timeout=30;user=sa;pwd=")

datatable dt = new datatable();

dt = datatable)"select * from youtable", ;dt;

/。Slow down the conversation... Which Jane.

Set the keypress event of the textbox to be limited to the following **:p rivate void presskey time(object sender, keypresseventargs e).

int16 asc = ;

if (asc !=8 &&asc !=13)string keychar = ;

string t_str1, t_str2, reg;

textbox t = textbox)sender;

t_str1 = ,

t_str2 = +

tryt_str1 +=keychar + t_str2;

reg = d(:\d)$"

if (!reg)) throw new exception("invalid!")

true;Modify the regular expression of the black part can be made a variety of different restrictions, the above only limit the input format is 88:88:88, if you want to add the limit of the size of the input value, please modify the regular table by yourself.

；Set the controls to be public.

Define a static class and static variables, such as:

namespace client

Other interface calls.

namespace client

Through the student number, you can SQL out the name and then pass it on.