I am creating a practice SQL Server database project, and I'm trying to enter text into a SQL Server database through a Windows Form. I'm not sure if my text data was really entered to my database. How do I view if it was entered? I'm a beginner so please try to use beginner SQL and VS vocabulary. I've tried going to show table data but that shows that no data was entered so I'm assuming its not working. Whenever I hit the button it just gives me no response so I'm not sure.
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Data;
using System.Data.SqlClient;
namespace DBHotel
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
string connectionString = "Data Source=(LocalDB)\\MSSQLLocalDB;AttachDbFilename=C:\\Users\\Nicholas Hoffs\\source\\repos\\DBHotel\\DBHotel\\Hotel.mdf;Integrated Security=True";
private void instBttn_Click(object sender, EventArgs e)
{
string nameQuery = textInst.Text;
using(SqlConnection conn = new SqlConnection(connectionString))
{
using(SqlCommand cmd = new SqlCommand(nameQuery, conn))
{
conn.Open();
cmd.CommandText = "INSERT INTO Customers(name) VALUES(#nameQuery)";
cmd.Parameters.AddWithValue("nameQuery", nameQuery);
cmd.ExecuteNonQuery();
}
}
}
}
}
Help is very much appreciated, thanks!
I know this is nonintuitive but try using the # inside your AddWithValue:
cmd.Parameters.AddWithValue("#nameQuery", nameQuery);
EDIT: WARNING The below solution is at risk of sql injection, and is highly discouraged.
As you are using direct query in instead of using stored procedure, you can't pass parameter to SQL. Instead of passing parameter try using
cmd.CommandText = "INSERT INTO Customers(name) VALUES('" + nameQuery + "')";
this means we are just concatenating the value of variable "nameQuery" in the query itself. so no need of below statement
cmd.Parameters.AddWithValue("nameQuery", nameQuery);
Related
I am trying to connect to a database in C# and bring up certain data points. The database has numerous columns and tables and I simply want to display them in the console using Writeline(). Below is what I have so far. The code runs without error but does not display anything either.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Data.SqlClient;
using System.Data.Sql;
namespace SQLIntro
{
class Program
{
static void Main(string[] args)
{
using (SqlConnection connection = new SqlConnection("Server=[SQ_SIXTEEN];Database=[PocketCentral];User ID=[un];Password=[pw];Trusted_Connection=true"))
{
connection.Open();
using (SqlCommand command = new SqlCommand("SELECT * FROM tbl_Terminal", connection))
{
using (SqlDataReader reader = command.ExecuteReader())
{
while (reader.Read())
{
for (int i = 0; i < reader.FieldCount; i++)
{
Console.WriteLine(reader.GetValue(i));
}
Console.WriteLine();
}
}
}
}
}
}
}
The one thing is where the column info would go...The SQL command? or in the while loop?.
That code would actually throw an exception. You have surrounded the names with brackets in your connection string which would cause the connection to fail. Change it to:
using (SqlConnection connection = new SqlConnection("Server=SQ_SIXTEEN;Database=PocketCentral;Trusted_Connection=true"))
Note that when Trusted_Connection is true (windows authentication) you don't use UserID and Password.
EDIT: Additional notes.
You would normally know your data content (your columnname and types). From SQL viewpoint it is suggested that you should list all your columns. ie: Instead of simply using "select *" use something like "select firstName, lastName, ... from ...".
As per the reader, instead of reader.GetValue[i] you use reader[index] and cast the type to what it should be like:
(int)reader[0]
(DateTime)reader["OrderDate"]
Integer indexing is faster but depends on column position where string indexing with column name is more readable.
EDIT2: Don't skip looking into LINQ. It is easier IMHO.
I am trying to simply insert values into an SQL table. The ID in the database cannot be AUTO_INCREMENT so I use MAX and +1. Not only will this code not make a new ID, it simply isn't inserting anything into the table.
Even in the debugger there are no errors or warnings, it just isn't showing up in the database itself..
Here is my code:
using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Windows;
using System.ComponentModel;
using System.Drawing;
using System.Text;
namespace WebApplication2
{
public partial class WebForm1 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void ButtonClick(object sender, EventArgs e){
using (var sqlConnection1 = new SqlConnection("Data
Source=SERVER; Initial Catalog = Metal; Integrated
Security = True"))
{
SqlDataAdapter cmd = new SqlDataAdapter();
using (var insertData = new SqlCommand("INSERT INTO ApptIn
(CONTROLNUMBER, CARRIERNAME, EXPECTEDNUMOFPIECES, EXPECTEDWEIGHT) VALUES
(#carrierSelectInput,
#pieceCountInput, #weightinput)")
{
SqlCommand generateApptNum = new SqlCommand();
View appNumView = new View();
insertData.Connection = sqlConnection1;
string carrierSelectInput = DropDownList1.Text;
string pieceCountInput = TextBox1.Text;
string weightInput = TextBox2.Text;
insertData.Parameters.Add("#carrierSelectInput",
carrierSelectInput.VarChar);
insertData.Parameters.Add("#pieceCountInput",
pieceCountInput.Int);
insertData.Parameters.Add("#weightInput",
weightInput.Int);
cmd.InsertCommand = insertData;
sqlConnection1.Open();
insertData.ExecuteNonQuery();
generateApptNum.ExecuteNonQuery();
sqlConnection1.Close();
}
}
}
}
}
EDIT: I have tried running the SQL into the DB and it gave an error, so I changed it(updated in code) but it puts in at ID=0...
I know you have already committed to your plan, but, I feel that I have to point out that, due to the sub select for the Max id value in your query, the insert statement has the potential to be much slower than a normal insert.
If you are planning on inserting a large number of rows or creating an API for use throughout the code I highly recommend either adjusting the column definition to be an identity column or to consider using a a sequence to generate the ids.
The issue could be that you need to specify the CommandType to be CommandType.Text on the insertData command. There is a lot going on in the original code with multiple sqlcommands being declared. I think the code could be simplified as such:
protected void ButtonClick(object sender, EventArgs e)
{
using (var sqlConnection1 = new SqlConnection("data source=testServer;initial catalog=testCat;integrated security=True;"))
using (var insertData = new SqlCommand("insert into tempExample (id, code, description) values ((select max(coalesce(id, 1)) from tempExample)+1, #code, #description)", sqlConnection1))
{
insertData.CommandType = CommandType.Text;
insertData.Parameters.AddWithValue("#code", "Testing4");
insertData.Parameters.AddWithValue("#description", "Testing3");
sqlConnection1.Open();
insertData.ExecuteNonQuery();
sqlConnection1.Close();
}
}
Update - I changed the code above to reflect a working test on my local machine. Note that the connection string format is different (lack of spaces).
I am currently trying to connect to a database made in MS SQL Server and insert a row when a button on a form is clicked. Below is my code and an explanation of what is going wrong.
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Data.SqlClient;
namespace WindowsFormsApplication10
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
SqlConnection myConnection = new SqlConnection("Data Source = (LocalDB)\\MSSQLLocalDB; AttachDbFilename = 'u:\\my documents\\visual studio 2015\\Projects\\WindowsFormsApplication10\\WindowsFormsApplication10\\InventoryDB.mdf'; Integrated Security = True; Connect Timeout = 30");
SqlCommand myCommand = new SqlCommand("INSERT INTO Table (Barcode, Item, Quantity) Values (123, 'Item 123', 5)", myConnection);
myConnection.Open();
myCommand.ExecuteNonQuery();
myConnection.Close();
}
}
}
I believe I have connected to the database, because in previous attempts I was getting an error at myConnection.Open(). Now I am getting an error at myCommand.ExecuteNonQuery(); which says:
SqlException was Unhandled: An Unhandled Exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll
Additional information: Incorrect syntax near the keyword 'Table'.
You can't use Table as the name for your table without qualifying it, since it's a SQL reserved word. Use [Table] instead if that is really your table name.
INSERT INTO [Table] (Barcode, Item, Quantity)...
Better yet, change the name of your table. Unless this is a copy/paste fail.
My first issue: I am trying to establish connection to MySql database, but I keep getting error when I debug it with Visual Studio:"Connection must be valid and open."
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Threading;
using MySql.Data.MySqlClient;
using MySql.Data.Types;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
MySqlConnection conn;
string myConnectionString;
myConnectionString = "server=localhost;User Id=root;database=test3";
using (conn = new MySqlConnection(myConnectionString))
{
DateTime startTime = DateTime.Now;
MySqlCommand cmd = new MySqlCommand("SELECT * FROM department");
// sleep for 2.5s
Thread.Sleep(2500);
conn.Open();
var reader = cmd.ExecuteReader();
conn.Close();
}
}
}
My second issue: if there a way to display all this on a ASP.NET Web form (I want to leave code on server side), but display data something like ListView or GridView? Thanks in advance
You need to call conn.Open() before using it.
You forgot to attach your connection to the command:
cmd.Connection = conn;
I think I'm missing an 'USING" statement in my class as I'm getting an error when I try to set the commandType to stored procedure. When I type 'cmd.CommandType =', Intellisense fails to find the 'CommandType.StoredProcedure (Note: the function is only partly roughed out). Thanks in advance!
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Configuration;
using System.Data.SqlClient;
namespace LegacyForms.Personal
{
public partial class FormBuilder : System.Web.UI.Page
{
protected void btnSubmit_Click(object sender, EventArgs e)
{
//Get the DB connection:
string ConnString = ConfigurationManager.AppSettings["AssociatedBank2011ConnectionString"];
SqlConnection conn = new SqlConnection(ConnString);
SqlCommand cmd = new SqlCommand("uspInsertPersonalAccountApplcation", conn);
cmd.Commandtype = **get error here!**
cmd.Parameters.AddWithValue("#AccountType", AcctType);
cmd.Parameters.AddWithValue("#AccountSubType", AcctSubType);
cmd.Parameters.AddWithValue("#CheckingOption", CheckOption);
conn.Open();
cmd.ExecuteNonQuery();
conn.Close();
}
}
}
using System.Data;
You need to reference System.Data. See the MSDN Reference for the CommandType Enumeration. Direct quote:
Namespace: System.Data
Assembly: System.Data (in System.Data.dll)
I'd also recommend the other using statement for your SqlConnection and SqlCommand objects. Since they both implement the IDisposable interface, you can do the following:
string ConnString = ConfigurationManager.AppSettings["AssociatedBank2011ConnectionString"];
using (SqlConnection conn = new SqlConnection(ConnString))
using (SqlCommand cmd = new SqlCommand("uspInsertPersonalAccountApplcation", conn))
{
cmd.Commandtype = CommandType.StoreProcedure;
cmd.Parameters.AddWithValue("#AccountType", AcctType);
cmd.Parameters.AddWithValue("#AccountSubType", AcctSubType);
cmd.Parameters.AddWithValue("#CheckingOption", CheckOption);
conn.Open();
cmd.ExecuteNonQuery();
}
That way, in the case that your code works correctly or throws an exception in the using block, your SqlConnection and SqlCommand will clean up after themselves.
In such situations you can press CTRL + . (ctrl + dot) to get a suggestion like do you want to add using System.Data...
P.S. Teach a men to fish ...