I know people are going to scream that this topic is all over the internet. I know, I've read them. And I still don't understand it. I simply want to populate my object from the results of a stored procedure. Now this stored procedure takes at least 2 parameters - an action and what to find.
#Action
#customername
The #Action simply determine what the stored procedure needs to do and returns the results. So for example if I want to update a customer, I'd call the sp through my object:
public class Customer()
{
//properties
public int UpdateCustomer()
{
using (SQLConnection connection = new SqlConnection(Helper.CnnVal("DataConnection")))
{
SQLCommand = new SqlCommand(Helper.Procedure("Customer"), connection);
command.CommandType = CommandType.StoredProcedure;
SqlParameterCollection parameterCollection = command.Parameters;
parameterCollection.Add("#Action", SqlDbType.NVarChar, -1).Value = "Update"
//complete the rest of it....
}
}
}
This works well. So the problem arises when I simply want to populate the object with the results of the sp. In this case I would pass "Retrieve" as the #Action parameter and this.customer_name as the #customername parameter to the sp.
But how do I put the results from the stored procedure into the object?
I have this...
public void GetCustomer()
{
using (SQLConnection connection = new SqlConnection(Helper.CnnVal("DataConnection")))
{
var retrieval = new DynamicParameters();
retrieval.Add("#Action", "Retrieve");
retrieval.Add("#name", this.customer_Name);
connection.Open():
connection.Execute(Helper.Procedure("Customer"), retrieval, commandType: CommandType.StoredProcedure);
}
}
But I don't think it's working.
Back a long time ago I used to run a "fetch" for PHP when I needed to populate an object. Should I go back to this?
You need to execute a SqlReader on the command, Something like this:
using (var connection = new SqlConnection("Connection"))
using (var command = new SqlCommand("Retrieve", connection))
{
command.CommandType = System.Data.CommandType.StoredProcedure;
command.Parameters.AddWithValue("#Action", "Retrieve");
command.Parameters.AddWithValue("#name", this.customer_Name);
connection.Open();
using (var reader = command.ExecuteReader())
{
while (reader.Read())
{
var item = new YourClass();
// You can use GetX() methods to get the value of the fields
item.Name = reader.GetString("name");
// You can also access the fields by using bracket notation
item.Age = (int)reader["age"];
// Be careful of nullable fields though!
}
}
}
Using #Encrypt0r advice and guidance I got it working:
public void GetCustomer() {
using (SqlConnection connection = new SqlConnection(Helper.CnnVal("DataConnection"))) {
SqlCommand command = new SqlCommand(Helper.Procedure("Customer"), connection);
command.CommandType = CommandType.StoredProcedure;
command.Parameters.AddWithValue("#Action", "Retrieve");
command.Parameters.AddWithValue("#name", this.customer_name);
connection.Open();
using (var reader = command.ExecuteReader()) {
while (reader.Read()) {
this.tbl_id = (int)reader["tbl_id"];
this.customer_name = (string)reader["customer_name"];
this.customer_id = reader.GetInt32(customer_id);
this.customer_address = (string)reader["customer_address"];
this.customer_city = (string)reader["customer_city"];
this.customer_state = (string)reader["customer_state"];
this.customer_zip = reader.GetInt32(customer_zip);
}
}
Related
I'm trying to create a generic function, using SqlClient in C#, which will accept a value for any column name and return the valid objects. My approach is to create a stored procedure which accepts values for every column, and where a value has not been provided it will be assume that any value is accepted. My code is as below (code is a little unfinished with regards the final requirement):
public async Task<List<OrganisationInstance>> GetOrganisationInstances(string name, int id)
{
List<OrganisationInstance> responses = new List<OrganisationInstance>();
using (SqlConnection connection = new SqlConnection(connectionString))
{
try
{
await connection.OpenAsync();
using (SqlCommand command = new SqlCommand(OrganisationInstancesSP.READ_ORGANISATION, connection))
{
command.CommandType = CommandType.StoredProcedure;
command.Parameters.Add("Id", SqlDbType.BigInt).Value = 2;
command.Parameters.Add("CreationDate", SqlDbType.DateTime).Value = "2021-12-14 23:59:25.837";
command.Parameters.Add("CompanyName", SqlDbType.VarChar).Value = "xxxxxxxxxx";
command.Parameters.Add("Postcode", SqlDbType.VarChar).Value = "xxxxxxxxxxx";
command.Parameters.Add("FormationDate", SqlDbType.DateTime).Value = "2021-12-14 23:59:25.837";
command.Parameters.Add("NodeId", SqlDbType.Int).Value = id;
SqlDataReader reader = await command.ExecuteReaderAsync();
while (reader.Read())
responses.Add(new OrganisationInstance { CompanyName = reader["CompanyName"].ToString(), Id = Convert.ToInt32(reader["Id"]) });
}
}
catch (DbException ex)
{
return null;
}
finally
{
connection.Close();
}
}
return responses;
}
The query returns the expected object, when all values are set to the values of an instance/row in the database. However, I cannot find a way to set the column to allow any value.
In SQL, it would be possible to say WHERE CreationDate = CreationDate , which would translate to:
command.Parameters.Add("CreationDate", SqlDbType.DateTime).Value = "CreationDate";
However, this doesn't work in SqlClient. Can anyone suggest how I might achieve this?
I wrote up this function to return a dataset, I was expecting a smaller dataset as there's only one value I was expecting back, but I get a rather bloated object back which I cannot find the value I am looking for, this is causing problems as I intend to use this function heavily.
I was hoping someone could spot what I am doing wrong, I have included the code, a screenshot of the returned object and what I am expecting. Any help would be greatly appreciated.
If I have not phrased anything in this question correctly feel free to let me know, I struggle to express my thoughts well.
public DataSet getPartnerParameter(string parameter)
{
using (var dbConnection = new SqlConnection(UnityHelper.IocContainer.Resolve<IConfigHelperService>().GetConnectionString("CASConnectionString")))
{
dbConnection.Open();
using (var dbCommand = new SqlCommand("GETPARTNERPARAMETER"))
{
dbCommand.CommandType = CommandType.StoredProcedure;
dbCommand.Connection = dbConnection;
SqlParameter lstrParameter = new SqlParameter("#Parameter", SqlDbType.VarChar);
lstrParameter.Value = parameter;
dbCommand.Parameters.Add(lstrParameter);
var ldaDPS = new SqlDataAdapter(dbCommand);
var ldstParameterValues = new DataSet();
ldaDPS.Fill(ldstParameterValues);
return ldstParameterValues;
}
}
}
This is what I am expecting to find
edit//
changed my code slightly but still not working.
public String[] getPartnerParameter(string parameter)
{
using (var dbConnection = new SqlConnection(UnityHelper.IocContainer.Resolve<IConfigHelperService>().GetConnectionString("CASConnectionString")))
{
dbConnection.Open();
SqlCommand dbCommand = new SqlCommand("GETPARTNERPARAMETER", dbConnection);
dbCommand.CommandType = CommandType.StoredProcedure;
SqlParameter lstrParameter = new SqlParameter("#Parameter", SqlDbType.VarChar);
lstrParameter.Value = parameter;
dbCommand.Parameters.Add(lstrParameter);
SqlDataReader reader = dbCommand.ExecuteReader();
string[] results = new string[2];
while (reader.Read())
{
results[0] = reader[0].ToString();
results[1] = reader[1].ToString();
}
if (results.Length < 1)
{
results[0] = "Cannot find Value";
results[1] = "S";
return results;
}
else
{
return results;
}
}
The error is this:
{"Procedure or function 'GETPARTNERPARAMETER' expects parameter '#Parameter', which was not supplied."}
The values you are looking for are probably in the dataSet.Tables[0].Rows[0] row.
However, if you are expecting one row back, a DataSet object seems like overkill. I would recommend avoiding the SqlDataAdapter/DataSet and instead use a SqlDataReader.
Untested code, but should give you the gist of how to use it:
using (SqlConnection connection = new SqlConnection(connectionString))
{
connection.Open();
SqlCommand dbCommand = new SqlCommand("GETPARTNERPARAMETER", connection);
dbCommand.CommandType = CommandType.StoredProcedure;
SqlParameter lstrParameter = new SqlParameter("#Parameter", SqlDbType.VarChar);
lstrParameter.Value = "LexisNexisCreditConsentRequired";
dbCommand.Parameters.Add(lstrParameter);
SqlDataReader reader = dbCommand.ExecuteReader();
while (reader.Read())
{
var yourValue = reader[0];
var yourDataType = reader[1];
}
}
A DataSet is an object which can contain many tables. It doesn't have to, but it can, and so it also has a number of fields, properties, and methods to support that role.
For this query, look at ldstParameterValues.Tables[0].Rows[0]. Within that row, you can also see the columns with another level of bracket-indexing:
DataRow row = ldstParameterValues.Tables[0].Rows[0];
var column0Value row[0];
var column1Value = row[1];
However, the type for these results is object. You'll need to either cast the values or use one of the GetX() methods on the datarow to get results with a meaningful type.
I'm using EF for fetching data from stored procedure in MS SQL. Stored procedure is returning table. (columns have same names as properties in my object)
List<MyObject> result =
db.ExecuteStoreQuery<MyObject>("EXEC [dbo].myProcedure]").ToList();
Is there a way how to do this without Entity Framework? (with SqlCommand)
Thanks.
Sure, you could use basic ADO.NET like this:
var list = new List<MyObject>();
using (SqlConnection c = new SqlConnection("your connection string"))
{
var cmd = new SqlCommand("EXEC [dbo].myProcedure", c);
cmd.CommandType = CommandType.StoredProcedure;
using (SqlDataReader sdr = cmd.ExecuteReader())
{
while (sdr.Read())
{
var o = new MyObject
{
Property1 = sdr.GetString(0),
Property2 = sdr.GetInt32(1),
etc...
}
list.Add(o);
}
}
}
Now keep in mind that the SqlDataReader gets values by index, so if your SELECT list looked like this, Property1, Property3, Property2, then they would be indexed as so.
I am trying to return a data object from my database so that i can access (for example) a customer ID within my ASP.NET website. Upon a customer logging in the object is returned. However, i am getting the error:
'Invalid attempt to read when no data is present.'
I have completed an sql query on the database (Executing my stored procedure) which returns the correct information, so i know it is there. I can only presume that there is something wrong with the following method:
using (SqlConnection sqlConn = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString))
{
using (SqlCommand sqlComm = new SqlCommand("Select_Customer_By_UserName_And_Password", sqlConn))
{
sqlComm.Connection.Open();
try
{
sqlComm.CommandType = CommandType.StoredProcedure;
sqlComm.Parameters.Add("#Username", SqlDbType.NVarChar, 25).Value = pUsername;
sqlComm.Parameters.Add("#Password", SqlDbType.NVarChar, 25).Value = pPassword;
using (SqlDataReader sqlDR = sqlComm.ExecuteReader(CommandBehavior.SingleRow))
{
if (sqlDR.HasRows)
{
//Creating the new object to be returned by using the data from the database.
return new Customer
{
CustomerID = Convert.ToInt32(sqlDR["CustomerID"])
};
}
else
return null;
}
}
catch (Exception)
{
throw;
}
finally
{
sqlComm.Connection.Close();
}
}
}
You need to call sqlDR.Read(), otherwise the "record pointer" will to point to a record. HasRows only indicates there are actually rows you can read. To read each row (or just the first one), you need to call Read once or in a while loop.
For example:
if (reader.HasRows)
{
while (reader.Read())
...
}
Your code should read:
using (SqlDataReader sqlDR = sqlComm.ExecuteReader(CommandBehavior.SingleRow))
{
if (sqlDR.Read())
{
//Creating the new object to be returned by using the data from the database.
return new Customer
{
CustomerID = Convert.ToInt32(sqlDR["CustomerID"])
};
}
else
return null;
}
By the way: congrats on using using and parameterized queries!
This is a question from an experienced beginner!
Using ASP.NET 4 C# AND SQL server,
I have a connection string in web.config to myDatabase named "myCS".
I have a database named myDB.
I have a table named myTable with a primary key named myPK
What are the NECESSARY lines of code behind (minimal code) to create a SQL connection, then select from myTable where myPK=="simpleText"
it will probably include:
sqlconnection conn = new sqlconnection(??? myCS)
string SQLcommand = select * from myDB.myTable where myPK==myTestString;
sqlCommand command = new SqlCommand(SQL,conn);
conn.Open();
booleanFlag = ????
conn.Close();
conn.Dispose();
then
If ( theAnswer != NULL ) // or (if flag)
{
Response.Redirect("Page1.aspx");
}
else
{
Response.Redirect("Page2.aspx");
}
Here is a limited simple tutorial:
First, you want to have a class to do the hard work for you, then you will use it with ease.
First, you have to crate the connection string in your web.config file and name it.
Here it is named DatabaseConnectionString, but you may named it myCS as required in the question.
Now, in App_Code create a new class file and name it SqlComm (this is just an example name) like:
using System;
using System.Data;
using System.Data.SqlClient;
using System.Web;
public class SqlComm
{
// this is a shortcut for your connection string
static string DatabaseConnectionString = System.Configuration.ConfigurationManager.ConnectionStrings["dbConStr"].ConnectionString;
// this is for just executing sql command with no value to return
public static void SqlExecute(string sql)
{
using (SqlConnection conn = new SqlConnection(DatabaseConnectionString))
{
SqlCommand cmd = new SqlCommand(sql, conn);
cmd.Connection.Open();
cmd.ExecuteNonQuery();
}
}
// with this you will be able to return a value
public static object SqlReturn(string sql)
{
using (SqlConnection conn = new SqlConnection(DatabaseConnectionString))
{
conn.Open();
SqlCommand cmd = new SqlCommand(sql, conn);
object result = (object)cmd.ExecuteScalar();
return result;
}
}
// with this you can retrieve an entire table or part of it
public static DataTable SqlDataTable(string sql)
{
using (SqlConnection conn = new SqlConnection(DatabaseConnectionString))
{
SqlCommand cmd = new SqlCommand(sql, conn);
cmd.Connection.Open();
DataTable TempTable = new DataTable();
TempTable.Load(cmd.ExecuteReader());
return TempTable;
}
}
// sooner or later you will probably use stored procedures.
// you can use this in order to execute a stored procedure with 1 parameter
// it will work for returning a value or just executing with no returns
public static object SqlStoredProcedure1Param(string StoredProcedure, string PrmName1, object Param1)
{
using (SqlConnection conn = new SqlConnection(DatabaseConnectionString))
{
SqlCommand cmd = new SqlCommand(StoredProcedure, conn);
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.Add(new SqlParameter(PrmName1, Param1.ToString()));
cmd.Connection.Open();
object obj = new object();
obj = cmd.ExecuteScalar();
return obj;
}
}
}
Okay, this only a class, and now you should know how to use it:
If you wish to execute a command like delete, insert, update etc. use this:
SqlComm.SqlExecute("TRUNCATE TABLE Table1");
but if you need to retrieve a specific value from the database use this:
int myRequiredScalar = 0;
object obj = new object();
obj = SqlComm.SqlReturn("SELECT TOP 1 Col1 FROM Table1");
if (obj != null) myRequiredScalar = (int)obj;
You can retrieve a bunch of rows from the database this way (others like other ways)
This is relevant to your sepecific question
int Col1Value = 0;
DataTable dt = new DataTable();
dt = SqlComm.SqlDataTable("SELECT * FROM myTable WHERE myPK='simpleText'");
if (dt.Rows.Count == 0)
{
// do something if the query return no rows
// you may insert the relevant redirection you asked for
}
else
{
// Get the value of Col1 in the 3rd row (0 is the first row)
Col1Value = (int)dt.Rows[2]["Col1"];
// or just make the other redirection from your question
}
If you need to execute a stored procedure with or without returning a value back this is the way to do that (in this example there are no returning value)
SqlComm.SqlStoredProcedure1Param("TheStoredProcedureName", "TheParameterName", TheParameterValue);
Again, for your specific question return the table using the SqlDataTable , and redirect if dt.Rows.Count >0
Have fun.
There are many ways: LINQ, SqlDataReader, SQLDataAdapter, according to what you want to read (single value, datatable ...), so here is an example:
using (SqlConnection con = new SqlConnection("SomeConnectionString"))
{
var cmd = new SqlCommand("select from myTable where myPK==N'"+ simpleText+ "'",con);
cmd.Connection.Open();
var sqlReader = cmd.ExecuteReader();
while(sqlReader.Read())
{
//Fill some data like : string result = sqlReader("SomeFieldName");
}
sqlReader.Close();
cmd.Connection.Close();
cmd.Dispose();
}