How to convert combobox1.selectedvalue to string

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I have two tables, tbl1 have primary key with string, tbl2 have foreign key to that primary key ,when I try to insert into tbl2 value from combobox.Selected value
this error was occurred
Conversion failed when converting the nvarchar value 'FMCS17002' to data type int.

I try to use

CmbStudents.SelectedValue.ToString()
but not working 
and CmbStudents.SelectedItem
also not Working
Thank's ,,,

What I have tried:

cmd = New SqlCommand("insert into SupervisionAndExaminer values(@p1, @p2, @p3)", SqlSeverDB)

            cmd.Parameters.AddWithValue("@p1", CmbStudents.SelectedValue)
            cmd.Parameters.AddWithValue("@p2", CmbInstructorss.SelectedValue)
            cmd.Parameters.AddWithValue("@p3", CmbStudents.SelectedValue)
            cmd.ExecuteNonQuery()

Posted 10-May-17 23:38pm

NebroProg

Updated 11-May-17 0:24am

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CHill60 11-May-17 5:48am

The error is coming from your sql command. You must have a column defined as an int and you are trying to insert the value 'FMCS17002'.
Either parse the integer out of that text or change the column type on the database. I can't advise you further as we don't know anything about your table or the data you are trying to inser

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**Nirav Prabtani** · Answer 1 · 2017-05-10T23:47:00

The column where you are entering values has datatype integer

Make sure you are supplying data according to data type of a column of a table.

If you want to add "FMCS17002" then you must have to set datatype varchar(30) where 30 is a length of a character, You can set length according to your need, I have just set for example.

You can not insert this value as an integer.

I hope you got my point.

Jochen Arndt · Answer 2 · 2017-05-10T23:55:00

The error is

Conversion failed when converting the nvarchar value 'FMCS17002' to data type int

So you don't want a string (what SelectedValue already is in your case) but an integer. At least one of the database fields you are trying to set has the type int and the string value "FMCS17002" can't be converted to an integer.

So you have to change the database to use strings (NVARCHAR) for the corresponding fields or change the combo boxes to contain only integers (or strings representing valid integers so that they can be converted).

[EDIT]
The question has been changed after posting my solution:

Quote:
I have two tables, tbl1 have primary key with string, tbl2 have foreign key to that primary key ,when I try to insert into tbl2 value from combobox.Selected value

You have to query the ID from tbl1 first using the corresponding combo box string:

SQL

SELECT id FROM tbl1 WHERE name=selected_value

and pass the returned ID as parameter to the INSERT command.
[/EDIT]

NebroProg · Answer 3 · 2017-05-11T00:24:00

Solution 4

Thank you my friends ^^
the error in my code I exchange the positions of comboboxes and repeat

CmbStudents.SelectedValue

and there is another error in function that fill my combobox
The Problem was solved ^^

Posted 11-May-17 0:24am

NebroProg

How to convert combobox1.selectedvalue to string

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