SQL update statement in C

Question

I have table   Student      P ID   LastName  FirstName  Address  City     1        Hansen    Ola                    2        Svendson   Tove    3        Petterson   Kari    4        Nilsen       Johan    and so on    How do i change edit code in C    string firstName    Ola    string  lastName   Hansen    string  address    ABC    string city    Salzburg     string connectionString   System Configuration ConfigurationManager                            ConnectionStrings  LocalDB   ConnectionString    using  SqlConnection connection   new SqlConnection connectionString        using  SqlCommand command   connection CreateCommand           command CommandText    INSERT INTO Student  LastName  FirstName  Address  City                             VALUES   ln   fn   add   cit        command Parameters AddWithValue   ln   lastName      command Parameters AddWithValue   fn   firstName      command Parameters AddWithValue   add   address      command Parameters AddWithValue   cit   city       connection Open        command ExecuteNonQuery        connection Close          to edit entry  where Lastname field has lastname value and FirstName field has firstname  value     I dont want to use like this    UPDATE Persons  SET Address  Nissestien 67   City  Sandnes    WHERE LastName  Tjessem      AND FirstName  Jakob    and i edited my original statement to    command CommandText    UPDATE Student LastName  FirstName  Address  City      VALUES   ln   fn   add   cit  WHERE LastName      lastName                                  AND FirstName       firstName        but the statement is not getting executed  why is it throwing SQL exception   Is there nay solution to it

User · Answer

I dont want to use like this   That is the syntax for Update statement in SQL  you have to use that syntax otherwise you will get the exception    command Text    UPDATE Student SET Address    add  City    cit Where FirstName    fn AND LastName    ln     and then add your parameters accordingly    command Parameters AddWithValue   ln   lastName   command Parameters AddWithValue   fn   firstName   command Parameters AddWithValue   add   address   command Parameters AddWithValue   cit   city

User · Answer

string constr     Data Source  LocalDB  v11 0 Initial Catalog Bank Integrated Security True Pooling False   SqlConnection con   new SqlConnection constr   DataSet ds   new DataSet    con Open    SqlCommand cmd   new SqlCommand   UPDATE Account  SET name   Aleesha  CID   24 Where name  Areeba and CID  11     cmd ExecuteNonQuery

User · Answer

private void button4 Click object sender  EventArgs e                String st    DELETE FROM supplier WHERE supplier id      textBox1 Text           SqlCommand sqlcom   new SqlCommand st  myConnection           try                       sqlcom ExecuteNonQuery                MessageBox Show                            catch  SqlException ex                        MessageBox Show ex Message                          private void button6 Click object sender  EventArgs e                String st    SELECT   FROM suppliers            SqlCommand sqlcom   new SqlCommand st  myConnection           try                       sqlcom ExecuteNonQuery                SqlDataReader reader   sqlcom ExecuteReader                DataTable datatable   new DataTable                datatable Load reader               dataGridView1 DataSource   datatable                MessageBox Show  LEFT OUTER                        catch  SqlException ex                        MessageBox Show ex Message

User · Answer

command Text    UPDATE Student    SET Address    add  City    cit   Where FirstName    fn and LastName    add      nbsp

User · Answer

String st    UPDATE supplier SET supplier id       textBox1 Text      supplier name       textBox2 Text                WHERE supplier id       textBox1 Text           SqlCommand sqlcom   new SqlCommand st  myConnection           try                       sqlcom ExecuteNonQuery                MessageBox Show  update successful                      catch  SqlException ex                        MessageBox Show ex Message

User · Answer

Please  never use this concat form    String st    UPDATE supplier SET supplier id       textBox1 Text      supplier name       textBox2 Text            WHERE supplier id       textBox1 Text    use    command Parameters AddWithValue   attribute   value     Always work object oriented   Edit  This is because when you parameterize your updates it helps prevent SQL injection

User · Answer

This is not a correct method of updating record in SQL   command CommandText    UPDATE Student LastName  FirstName  Address  City  VALUES   ln   fn   add   cit  WHERE LastName      lastName      AND FirstName      firstName        You should write it like this   command CommandText    UPDATE Student  SET Address    add  City    cit Where FirstName    fn and LastName    add     Then you add the parameters same as you added them for the insert operation

User · Answer

If you don t want to use the SQL syntax  which you are forced to   then switch to a framework like Entity Framework or Linq-to-SQL where you don t write the SQL statements yourself

User · Answer

There is always a proper syntax for every language  Similarly SQL Structured Query Language  has also specific syntax for update query which we have to follow if we want to use update query  Otherwise it will not give the expected results

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