Visual Basic and SQL Server – Deleting Data

In order to delete data in an SQL Server database, the SQL ‘Delete’ statement needs to be used. The following example deletes a record with a specific ‘id’ from the ‘person’ table, which was used in the examples for selecting, inserting and updating data.

Deleting data works in a similar way to the other examples, where a parameterised query is used. Firstly, a connection to the database is established, then the query parameter for the ‘id’ of the record to be deleted is defined as a variable, which is bound in to the following SQL statement. The SQL statement is then executed and a confirmation message is displayed. The declaration and execution of the SQL statement is wrapped in a ‘Try-Catch-Finally’ block to catch any errors that may arise and close the database connection at the end.

' Database connection variable.
Dim connect = New SqlConnection(
    "Server=localhost\MSSQLSERVERDEMO; Database=Demo;" &
    "User Id=DemoUN; Password=DemoPW")


    ' Connect to database.

Catch ex As Exception

    ' Confirm unsuccessful connection and stop program execution.
    Console.WriteLine("Database connection unsuccessful.")

End Try


    ' Query parameter.
    Dim id As Integer = 2

    ' Query text.
    Dim sqlText As String =
        "DELETE FROM person " &
        "WHERE id = @id"

    ' Query text incorporated into SQL command.
    Dim sqlDelete As New SqlCommand(sqlText, connect)

    ' Bind the parameter to the query.
    sqlDelete.Parameters.AddWithValue("@id", id)

    ' Execute SQL.

    ' Confirm successful deletion of person information.
    Console.WriteLine("Person information deleted successfully.")

Catch ex As Exception

    ' Confirm error deleting person information and exit.
    Console.WriteLine("Error deleting person information.")


    ' Close the database connection.

End Try

The contents of the ‘person’ table now looks as follows.

id firstname lastname title dob
1 Bob Smith Mr 1980-01-20
3 Fred Bloggs Mr 1975-05-07
4 Alan White Mr 1989-03-20
5 Fiona Bloggs Mrs 1985-05-19