I am using the following code in order to insert some data into my SQL Server table. There isn't any error shown, but the table doesn't insert the values. What is wrong with it?
string sqlTxt1 = "INSERT INTO Users (ChatId , UserName) VALUES (#ChatId, #from)";
SqlCommand cmd1 = new SqlCommand(sqlTxt1, con);
cmd1.Parameters.AddWithValue("#ChatId", 12345);
cmd1.Parameters.AddWithValue("#from", "usrnm");
con.Open();
cmd1.ExecuteNonQuery();
//int recordsAffected =cmd1.ExecuteNonQuery();
con.Close();
As I put the code in a button and set the ChatId in the table as a primary key, I get an error when I click it twice, so I think the code is correct, but why the table doesn't get those values in the first click?
It should be string sqlTxt1 = "INSERT INTO Users (ChatId , UserName) VALUES (#ChatId, #from)";. You need to pass #from also.
You are inserting not updating the table. So when you click the second time, it tries to insert the record with the same primary key into the table again. You cannot insert the same value for the primary key in the table more than once, it will be a primary key violation. The primary key is always unique.
Related
After I try to insert a row into database and it fails due to duplicate (not primary key collision - another key), how do I get the primary key of the colliding row that prevented the insert?
Example:
The table:
CREATE TABLE `my_table` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`unique_value` varchar(60) NOT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `unique_data` (`unique_values`),
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
Some initial data:
INSERT INTO `my_table`(`unique_value`) VALUES ('unique string 1');
INSERT INTO `my_table`(`unique_value`) VALUES ('unique string 2');
And now, this will fail because of the collision in the index:
MySqlConnection conn = new MySqlConnection(connString);
conn.Open();
MySqlCommand comm = conn.CreateCommand();
comm.CommandText = "INSERT INTO `my_table`(`unique_value`) VALUES 'unique string 2'";
comm.ExecuteNonQuery();
conn.Close();
Can I get the primary key of the colliding row without making another query?
while creating the table you can use "Identity" keyword which will do all the "not null and Auto Increment" Stuff.
But this is for MsSQL
Try this:
create table my_table
(
ID int Primary key identity,
unique_value varchar(60) NOT NULL
)
As you said this that you are not worry about PK hence you can check the value of the column which has unique index.If there is already a raw with the value that you passing in new row then you are trying to insert duplicate otherwise not.
I'm developing a WinForm desktop application for users to input employees retirement data, using SQL Server 2008 as DB.
One of the tables that gets part of the user data has a reference to another table whose records were defined at design time, adding a Foreign Key constraint for consistency.
CREATE TABLE tbCongedo (
ID int IDENTITY(0,1) PRIMARY KEY,
ID_ANAGRAFICA int NOT NULL,
ID_TIPOLOGIA int NOT NULL,
DECORRENZA datetime NOT NULL,
PROT_NUM nvarchar(7) NOT NULL,
PROT_DATA datetime NOT NULL
);
CREATE TABLE tbTipologia (
ID int IDENTITY(0,1) PRIMARY KEY,
TIPOLOGIA nvarchar(20)
);
INSERT INTO tbTipologia VALUES ('CONGEDO'), ('POSTICIPO'), ('ANTICIPO'), ('REVOCA'), ('DECESSO')
ALTER TABLE tbCongedo
ADD CONSTRAINT FK_tbCongedo_tbTipologia
FOREIGN KEY (ID_TIPOLOGIA) REFERENCES tbTipologia(ID)
Then, I have this code that should execute the INSERT statement
public int Insert(SqlConnection Connessione)
{
using (SqlCommand Comando = new SqlCommand("INSERT INTO tbCongedo VALUES (#ID_ANAGRAFICA, #PROT_NUM, #PROT_DATA, #DECORRENZA, #ID_TIPOLOGIA); SELECT SCOPE_IDENTITY()", Connessione))
{
Comando.Parameters.AddWithValue("#ID_ANAGRAFICA", ID_ANAGRAFICA);
Comando.Parameters.AddWithValue("#PROT_NUM", PROT_NUM);
Comando.Parameters.AddWithValue("#PROT_DATA", PROT_DATA);
Comando.Parameters.AddWithValue("#DECORRENZA", DECORRENZA);
Comando.Parameters.AddWithValue("#ID_TIPOLOGIA", ID_TIPOLOGIA);
ID = Int32.Parse(Comando.ExecuteScalar().ToString());
}
return ID;
}
but I'm given this SqlException:
The INSERT statement conflicted with the FOREIGN KEY constraint "FK_tbCongedo_tbTipologia". The conflict occurred in database "Scadenziario_ver4_TEST", table "dbo.tbTipologia", column 'ID'
These are the data that I was trying to get inserted in the table:
ID_ANAGRAFICA = 2
ID_TIPOLOGIA = 0
PROT_DATA = {16/03/2018 00:00:00}
DECORRENZA = {16/03/2018 00:00:00}
PROT_NUM = 123456
Funny thing is that when I try to insert those same data manually through SQL Server Management Studio, I'm given no error at all.
Thanks.-
Try specifying fields: (col_name1, col_name2, ...).
Without that the VALUES may not be applied as how you might hope. Variable names are NOT automagically matched with similarly-named columns.
So like this:
... new SqlCommand
(
"INSERT INTO tbCongedo " +
" (ID_ANAGRAFICA, PROT_NUM, PROT_DATA, DECORRENZA, ID_TIPOLOGIA) "
"VALUES (#ID_ANAGRAFICA, #PROT_NUM, #PROT_DATA, #DECORRENZA, #ID_TIPOLOGIA); " +
"SELECT SCOPE_IDENTITY()", Connessione
)
...
I think the problem isn't in the data but in the INSERT statement itself. You are trying to insert the values to the wrong columns using the wrong order. To solve the issue you should either specify the columns in the INSERT statement or correct the order of the values. In your case the query will try to insert the value of #PROT_NUM in the ID_TIPOLOGIA instead.
I have a table SupplierMaster in a SQL Server database with a column SUPPLIERNAME.
I want to edit saved supplier name using stored procedure with below query
ALTER PROCEDURE [dbo].[usp_SupplierMasterUpdateDetails]
(
#SUPPLIERNAME NVARCHAR(50)
)
AS
BEGIN
UPDATE [dbo].[SupplierMaster]
SET [SUPPLIERNAME] = #SUPPLIERNAME
WHERE [SUPPLIERNAME] = #SUPPLIERNAME
END
and I run the BELOW code through "UPDATE BUTTON" to update the data.
string connString = ConfigurationManager.ConnectionStrings["dbx"].ConnectionString;
using (SqlConnection conn = new SqlConnection(connString))
{
using (SqlCommand cmd = new SqlCommand("usp_SupplierMasterUpdateDetails", conn))
{
cmd.CommandType = CommandType.StoredProcedure;
// Parameter
cmd.Parameters.AddWithValue("SUPPLIERNAME", AddSupplierTextBox.Text);
// Open Connection
conn.Open();
// ExecuteReader (Select Statement)
// ExecuteScalar (Select Statement)
// ExecuteNonQuery (Insert, Update or Delete)
cmd.ExecuteNonQuery();
MessageBox.Show("SUCCESSFULLY UPDATED", "Successful", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
}
But its not updating the selected data.
Please advice and assist me to correct the code for proper work.
You have multiple issues there.
First you need to fix your update query just as Thomas Levesque suggested.
a SQL Server table needs a primary key to be able to uniquely identify a record, for updates for example.
The easiest thing you could do is set that primary key to be identity of type int and make it self generating. Your supplier table could look like this :
SupplierID int, Primary Key, identity
SupplierName nvarchar(100)
Now, when you do an update, you would do it like this:
Update SupplierMaster
Set SupplierName = #supplierName
Where SupplierID = #suplierID
Such a SQL statement will return an int value. This return value will tell you how many SQL rows this update statement has changed. If it says 0 then it means that the SQL statement could not find that id you passed through and nothing changed. If it says 1, then the record was found and updated, if you get more than 1 you have an issue with the SQL statement and multiple rows were updated.
In your code check for this return value and that's how you determine if your update statement was successful or not.
I'm trying to insert two data columns into my SQL Server database but I get an error at the code line -> cmd.ExecuteNonQuery();
Cannot insert the value NULL into column OrderID, table RestaurantApp.dbo.Junc_Order; column does not allow nulls. INSERT fails.
The OrderID column is actually the primary key in my data table. I set it identity(1, 1) and want to insert other data and meanwhile it can insert 1, 2, 3, 4....automatically.
Here is the part of my code:
string insertString = "INSERT INTO Junc_Order(ID, Quantity)values (#ID, #Quantity)";
SqlCommand cmd = new SqlCommand(insertString, conn);
cmd.Parameters.AddWithValue("#ID", r_ID);
cmd.Parameters.AddWithValue("#Quantity", r_Quantity);
cmd.ExecuteNonQuery();
I already get connection with database ahead of these codes, so the problem should not be that.
Updated Junc_Order table design:
OrderID (PK,FK,int,not null)
ID(FK,int,not null)
Quantity(int,not null)
By viewing your question, it seems that your insert query is not correct:
First of all, you don't need to insert "OrderID" as it is primary key identity so sql server automatically insert it.
second, somewhere you are getting "r_ID" as null that's why you are facing error.Verify it and modify your code with the following:
string insertString = "INSERT INTO Junc_Order(Quantity) values(#Quantity)";
SqlCommand cmd = new SqlCommand(insertString, conn);
cmd.Parameters.AddWithValue("#Quantity", r_Quantity);
cmd.ExecuteNonQuery();
I have a C# app with have to use SQL Server database with 1 table (All_Data) and 5 columns (ID, Name, Surename, Age,Location)
Before inserting a new row how can I find out or get the value of the last ID in the table
I have a following code but it,a not work well
string query = "SELECT MAX(ID) FROM All_Data";
SqlCommand comSelect;
comSelect = new SqlCommand(query, connection);
int ID = (int)comSelect.ExecuteScalar();
ERROR message:
ExecuteScalar: Connection property has not been initialized
Please help me
First, from your code it is not clear what is the value of the variable connection.
From the error message it seems that you don't have initialized this variable and thus you get the error. (connection = new SqlConnection(....);)
However, this is not the correct way to handle this scenario.
You need to make the ID column an IDENTITY column and then don't try to retrieve its value before executing any INSERT.
An IDENTITY column receives its value directly from the database when there is a new record to insert. And letting the database code work on this data it is the best option if you want to be safe from concurrency issues.
If you need to retrieve the ID value after an INSERT query because you need it as a Foreign Key in other tables or for your own code, then you could simply use the T-SQL command
SELECT SCOPE_IDENTITY()
For example, suppose you have to insert a record in that table, and you want to know the IDENTITY value assigned to the ID column
string query = #"INSERT INTO All_Data(Name,Surename,Age,Location)
VALUES(#name, #surname, #age, #loc);
SELECT SCOPE_IDENTITY()";
using(SqlConnection connection = new SqlConnection(connectionString))
using(SqlCommand cmd = new SqlCommand(query, connection))
{
connection.Open();
cmd.Parameters.AddWithValue("#name", yourNameValue);
.... other parameters ...
int newID = Convert.ToInt32(cmd.ExecuteScalar());
}
As you can see, this code doesn't try to pass a value for the ID column. It pass just the other fields with a parameterized query. But at the end of the first query there is a call to SELECT SCOPE_IDENTITY() and this returns whatever value the database has assigned to the column ID (of course you should have set the IDENTITY property on the field).
This will work correctly in multiuser and concurrent scenario
The error fires when the command doesn't have a connection. Please check connection is open.
Error saysExecuteScalar: Connectio property has not been initialized
double Check your connection string whether it is defined properly. You can check here to know how to define connection string.
you have not opened connection so open it before use :
comSelect = new SqlCommand(query, connection);
connection.Open();
int ID = (int)comSelect.ExecuteScalar();
connection.Close();