I'm trying something out but cant figure it out. So what i'm trying is that if the user inputs something inside txtISN and it already exists inside of the database, the record wont be inserted. I also want a error msg to pop up when a record wasnt inserted and when a record is inserted I want an message to pop up saying that the record was inserted succesfully.
Thanks for the help y'all!
string _connStr = #"Data Source = EJQ7FRN; Initial Catalog = BES; Integrated Security = True";
string _query = "INSERT INTO [BES_S] (ISN,Titel,Name) values (#ISN,#Titel,#Name)";
using (SqlConnection conn = new SqlConnection(_connStr))
{
using (SqlCommand comm = new SqlCommand())
{
comm.Connection = conn;
comm.CommandType = CommandType.Text;
comm.CommandText = _query;
comm.Parameters.AddWithValue("#ISN", txtISN.Text);
comm.Parameters.AddWithValue("#Titel",txtTitel.Text);
comm.Parameters.AddWithValue("#Name", txtName.Text);
try
{
conn.Open();
comm.ExecuteNonQuery();
}
catch (SqlException ex)
{
}
}
}
You need to change your query a bit, but you can use MySql's DUAL keyword to do this:
string _connStr = #"Data Source = EJQ7FRN; Initial Catalog = BES; Integrated Security = True";
string _query = "INSERT INTO [BES_S] (ISN,Titel,Name) ";
_query = _query + " SELECT #ISN, #Titel, #Name FROM DUAL";
_query = _query + " WHERE NOT EXISTS (SELECT ISN WHERE ISN=#ISN)";
using (SqlConnection conn = new SqlConnection(_connStr))
{
using (SqlCommand comm = new SqlCommand())
{
comm.Connection = conn;
comm.CommandType = CommandType.Text;
comm.CommandText = _query;
comm.Parameters.AddWithValue("#ISN", txtISN.Text);
comm.Parameters.AddWithValue("#Titel",txtTitel.Text);
comm.Parameters.AddWithValue("#Name", txtName.Text);
try
{
conn.Open();
comm.ExecuteNonQuery();
}
catch (SqlException ex)
{
}
}
}
DUAL is like a dummy table that you can use to SELECT from.
Let the database take care of this using a unique constraint/index:
alter table bes_s add constraint unq_bes_ISN unique (ISN);
This will cause the database to generate an error if a duplicate ISN is inserted. You can put one or more columns for the unique constraint (in case this single column is not the exact definition of uniqueness).
Related
I created the following code:
public static bool setHeadword(int id, string headword)
{
SqlConnection conn = new SqlConnection();
conn.ConnectionString = "Data Source=(LocalDB)\\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\\pms.mdf;Integrated Security=True";
conn.Open();
SqlCommand command = new SqlCommand("UPDATE headwords SET Headword = #headword WHERE Id = #id", conn);
command.Parameters.AddWithValue("#headword", headword);
command.Parameters.AddWithValue("#id", id);
int result = command.ExecuteNonQuery();
conn.Close();
return true;
}
But the code doesn't work because the value in the database doesn't change.
If I run the code manually in the database the change takes place. But it won't work with C#.
Also the result variable are holding the right number of affected rows (1 in this case).
I'm not sure I have to flush the changes or something else.
Thanks for your help and best regards
Franz
static void Update(int id, string headword)
{
try
{
//You should create connectionString with correct details otherwise fail connection
string connectionString =
"server=.;" +
"initial catalog=employee;" +
"user id=sa;" +
"password=123";
using (SqlConnection conn =
new SqlConnection(connectionString))
{
conn.Open();
using (SqlCommand cmd =
new SqlCommand("UPDATE headwords SET Headword=#headword" +
" WHERE Id=#Id", conn))
{
cmd.Parameters.AddWithValue("#Id", id);
cmd.Parameters.AddWithValue("#headword", headword);
int rows = cmd.ExecuteNonQuery();
}
}
}
catch (SqlException ex)
{
//Handle sql Exception
}
}
After searching for about an hour it appears this is the correct way to use the oledb libary to insert a record to an access database however it doesnt work for me , HELP...
InitializeComponent();
System.Data.OleDb.OleDbConnection conn = new
System.Data.OleDb.OleDbConnection();
// TODO: Modify the connection string and include any
// additional required properties for your database.
conn.ConnectionString = #"Provider = Microsoft.ACE.OLEDB.12.0; Data Source = \\crd-a555-015.occ.local\c$\Users\james.piper\Documents\Visual Studio 2015\Projects\Project V1\Project Database.accdb";
try
{
OleDbCommand cmd = new OleDbCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = "INSERT INTO Work_Done (employee,client,project,task,hours)" + " VALUES (#employee,#client,#project,#task,#hours)";
cmd.Parameters.AddWithValue("#employee", user.employee);
cmd.Parameters.AddWithValue("#client", listBox1.SelectedItem.ToString());
cmd.Parameters.AddWithValue("#project", listBox2.SelectedItem.ToString());
cmd.Parameters.AddWithValue("#task", listBox3.SelectedItem.ToString());
cmd.Parameters.AddWithValue("#hours", listBox4.SelectedItem.ToString());
conn.Open();
cmd.ExecuteNonQuery();
conn.Close();
}
catch (Exception ex)
{
MessageBox.Show("sql insert fail");
}
I would write this code like this:
var connectionString = #"Provider = Microsoft.ACE.OLEDB.12.0; Data Source = \\crd-a555-015.occ.local\c$\Users\james.piper\Documents\Visual Studio 2015\Projects\Project V1\Project Database.accdb";
var query = "INSERT INTO Work_Done (employee,client,project,task,hours) VALUES (#employee,#client,#project,#task,#hours)";
using (var conn = new OleDbConnection(connectionString))
{
using(var cmd = new OleDbCommand(query, conn))
{
// No need to specifiy command type, since CommandType.Text is the default
// I'm assuming, of course, your parameter data types. You should change them if my assumptions are wrong.
cmd.Parameters.Add("#employee", OleDbType.Integer).Value = user.employee;
cmd.Parameters.Add("#client", OleDbType.Integer).Value = Convert.ToInt32(listBox1.SelectedItem);
cmd.Parameters.Add("#project", OleDbType.Integer).Value = Convert.ToInt32(listBox2.SelectedItem);
cmd.Parameters.Add("#task", OleDbType.Integer).Value = Convert.ToInt32(listBox3.SelectedItem);
cmd.Parameters.Add("#hours", OleDbType.Integer).Value = Convert.ToInt32(listBox4.SelectedItem);
try
{
conn.Open();
cmd.ExecuteNonQuery();
conn.Close();
}
catch (Exception ex)
{
MessageBox.Show($"sql insert fail: {ex}");
}
}
}
The major changes are these:
use the Using statement for each instance of a class that implements the IDisposable interface.
Using constructors with parameters to make the code shorter (and more readable, IMHO).
Note that the constructor of the OleDbCommand also has the OleDbConnection object. In your code, you didn't specify the active connection to the command.
Adding parameters with Add and not AddWithValue. Read this blog post to find out why.
I am trying to insert data into a database that I have that has a table called EmployeeInfo
The user is prompted to enter a last name and select a department ID (displayed to the user as either marketing or development) The column ID automatically increments.
Here is my Code behind
protected void SubmitEmployee_Click(object sender, EventArgs e)
{
var submittedEmployeeName = TextBox1.Text;
var submittedDepartment = selectEmployeeDepartment.Text;
if (submittedEmployeeName == "")
{
nameError.Text = "*Last name cannot be blank";
}
else
{
System.Data.SqlClient.SqlConnection sqlConnection1 =
new System.Data.SqlClient.SqlConnection("ConnString");
System.Data.SqlClient.SqlCommand cmd = new System.Data.SqlClient.SqlCommand();
cmd.CommandType = System.Data.CommandType.Text;
cmd.CommandText = "INSERT INTO EmployeeInfo (LastName, DepartmentID ) VALUES ('" + submittedEmployeeName + "', " + submittedDepartment + ")";
cmd.Connection = sqlConnection1;
sqlConnection1.Open();
cmd.ExecuteNonQuery();
sqlConnection1.Close();
}
}
The error I'm recieving is 'Arguement exception was unhandled by user code'
Here is a picture of it.
As requested. More details
If I had enough reputation, I would rather post this as a reply, but it might actually be the solution.
The reason why it stops there is because you are not providing a legit SqlConnection, since your input is: "ConnString", which is just that text.
The connection string should look something like:
const string MyConnectionString = "SERVER=localhost;DATABASE=DbName;UID=userID;PWD=userPW;"
Which in your case should end up like:
System.Data.SqlClient.SqlConnection sqlConnection1 = new System.Data.SqlClient.SqlConnection(MyConnectionString);
Besides that, you should build your connections like following:
using (SqlConnection con = new SqlConnection(MyConnectionString)) {
using (SqlCommand cmd = new SqlCommand())
{
cmd.CommandText = xxxxxx; // Your query to the database
cmd.Connection = con;
cmd.Connection.Open();
cmd.ExecuteNonQuery();
}
}
This will do the closing for you and it also makes it easier for you to nestle connections. I did a project recently and did the connection your way, which ended up not working when I wanted to do more than one execute in one function. Just important to make a new command for each execute.
The database is not storing information all on the same row. On the first page, when I click the button it records it and that's fine, it's stored. Then on the next page, when i click the button, it stores the information, but on a different row? Any solutions? Heres the problem, and code below.
PAGE 1
public void addInformationToDatabase()
{
string Sex = ddlGender.Text;
string Name = tbxName.Text;
string DOB = tbxDOB.Text;
string connectionString = WebConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
SqlConnection Con = new SqlConnection(connectionString);
SqlCommand command = new SqlCommand();
command.Connection = Con;
command.CommandType = CommandType.Text;
command.CommandText = "INSERT INTO [User] (GenderID,Name,DOB) VALUES(#Sex,#Name,#DOB)";
command.Parameters.AddWithValue("#Sex", Sex);
command.Parameters.AddWithValue("#Name", Name);
command.Parameters.AddWithValue("#DOB", DOB);
try
{
Con.Open();
command.ExecuteNonQuery();
}
catch (Exception ex)
{
Response.Write(ex.Message);
}
finally
{
Con.Close();
}
}
2ND PAGE
public void save()
{
string checkboxSelection = CheckBoxList1.SelectedItem.ToString();
string connectionString = WebConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
SqlConnection Con = new SqlConnection(connectionString);
SqlCommand c = new SqlCommand();
c.Connection = Con;
c.CommandType = CommandType.Text;
c.CommandText = "INSERT INTO [User] (Ans1) VALUES(#Ans1)";
c.Parameters.AddWithValue("#Ans1", checkboxSelection);
try
{
Con.Open();
c.ExecuteNonQuery();
}
catch (Exception ex)
{
Response.Write(ex.Message);
}
finally
{
Con.Close();
}
}
Any help appreciated
your first page needs to get the ID back following the insert and then your second page needs to do an update based on that ID, not a subsequent insert.
There are a lot of resources about getting ids back - e.g How to get last inserted id?
(I'm assuming the id field uniquely identifies your row)
first query -
c.CommandText = "INSERT INTO [User] (Ans1) VALUES(#Ans1); SELECT SCOPE_IDENTITY()";
...
int userID = (Int32) c.ExecuteScalar();
you'll need to pass that ID to your 2nd page and change the insert to be an update:
"UPDATE User] SET Ans1 = #Ans1 WHERE Id = #id";
you'll also need to add the id as a parameter
c.Parameters.AddWithValue("#id", userID);
I have a table student (id, name). Then I have one textbox, for entering the name, when click on submit button, it inserts the data into the database. So how can I insert only to name, not id because id is auto increment?
I tried this
insert into student(id, name) values(,name)
but it is not insert to my table.
This is my code :
protected void Button1_Click(object sender, EventArgs e)
{
string test = txtName.Text;
SqlConnection conn = new SqlConnection(#"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Person.mdf;Integrated Security=True;User Instance=True");
string sql = "insert into student(name) values ('test')";
try
{
conn.Open();
SqlCommand cmd = new SqlCommand(sql, conn);
cmd.ExecuteNonQuery();
}
catch (System.Data.SqlClient.SqlException ex)
{
string msg = "Insert Error:";
msg += ex.Message;
}
finally
{
conn.Close();
}
}
INSERT INTO student (name) values ('name')
Omit the id column altogether, it will be populated automatically. To use your variable, you should parameterise your SQL query.
string sql = "INSERT INTO student (name) values (#name)";
conn.Open();
SqlCommand cmd = new SqlCommand(sql, conn);
cmd.Parameters.Add("#name", SqlDbType.VarChar);
cmd.Parameters["#name"].Value = test;
cmd.ExecuteNonQuery();
You should never attempt to do this by constructing a SQL string containing the input value, as this can expose your code to SQL injection vulnerabilities.
You better use parameters when you insert data.
try
{
string sql = "insert into student(name) values (#name)";
using (SqlConnection conn = new SqlConnection(connectionString))
{
conn.Open();
using (SqlCommand cmd = new SqlCommand(sql, conn))
{
cmd.Parameters.AddWithValue("#name", test); // assign value to parameter
cmd.ExecuteNonQuery();
}
}
}
catch (SqlException ex)
{
string msg = "Insert Error:";
msg += ex.Message;
}
You don't need to mention the ID in first part.
insert into student(name) values('name')
I was facing this problem and after trying various solution found at stack overflow, i could summarize the experience as follows:
commands executed in command shell of mssql like:
insert into table_name (val1,val2,val3,val4) VALUES ("val1","val2",0,"val4")
go
or
insert into table_name VALUES ("val1","val2",0,"val4")
go
work when typed directly in the mssql database prompt,
But when it is required to use the the insert statement from c#, it is required to be kept in mind that string needs to be surrounded by an additional pair of single quites, around the strings, like in:
SqlConnection cnn;
string connetionString = "Data Source=server_name;Initial Catalog=database_name;User ID=User_ID;Password=Pass_word";
cnn = new SqlConnection(connetionString);
SqlCommand myCommand = new SqlCommand("insert into table_name (val1,val2,val3,val4) VALUES ('val1','val2',0,'val4');", cnn);
//or
//SqlCommand myCommand = new SqlCommand(insert into table_name VALUES ('val1','val2',0,'val4');", cnn);
cnn.Open();
myCommand.ExecuteNonQuery();
cnn.Close();
the problem here is that most people, like myself, try to use <\"> in the place of double quotes <">that is implemented as in the above command line case, and SQL executor fails to understand the meaning of this.
Even in cases where a string needs to be replace, ensure that strings are surrounded by single quotation, where a string concatination looks like a feasible solution, like in:
SqlCommand myCommand = new SqlCommand("insert into table_name (val1,val2,val3,val4) VALUES ('"+val1+"','val2',0,'val4');", cnn);
string sql = "INSERT INTO student (name) values (#name)";
conn.Open();
SqlCommand cmd = new SqlCommand(sql, conn);
cmd.Parameters.Add("#name", SqlDbType.VarChar);
cmd.Parameters["#name"].Value = test;
cmd.ExecuteNonQuery();
Try the following query,
insert into student(name) values(name)
SQL Server internally auto increments the id column when u insert the data since u said it is auto increment. If it is not working, the u have to check the identity column in the db.
use the key word "identity" to auto increment the id column
Refer : http://technet.microsoft.com/en-us/library/aa933196(v=sql.80).aspx
create table table_name( id int PRIMARY KEY IDENTITY )
and you no need to mention the "id" in the insert query