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C#: An update query values not reflected in the intended oracle table

I'm trying to update some records in an oracle table using c#. I don't get errors, but when I have looked at the records that I wanted to update, I've found out that the records still have the same old values. to see if each query was executed successfully, I have used this line rowid= cmd.ExecuteNonQuery(); which returns the number of affected rows by the query 19583. The number that I have got is the number of rows in my table.
[OperationContract]
public int pushData(string CustomObjects)
{
List<CustomObject> myDeserializedObjList = (List<CustomObject>)Newtonsoft.Json.JsonConvert.DeserializeObject(CustomObjects,
typeof(List<CustomObject>));
string constr = "my connection string";
int rowid = 0;
using(OracleConnection con = new OracleConnection(constr)){
con.Open();
OracleCommand cmd = new OracleCommand();
cmd.Connection = con;
cmd.CommandType = CommandType.Text;
foreach (CustomObject element in myDeserializedObjList)
{
int num = element.num;
string mydate = element.mydate;
long num2 = element.num2;
string user = element.user;
string sqlStatement= "UPDATE CustomObjectS SET num = num,
mydate=mydate, num2=num2, user=user WHERE num = num";
OracleTransaction myTrans;
// Start a local transaction
myTrans = con.BeginTransaction();
// Assign transaction object for a pending local transaction
cmd.Transaction = myTrans;
cmd.CommandText=sqlStatement;
cmd.Parameters.Add(new OracleParameter("num", num));
cmd.Parameters.Add(new OracleParameter("user", user));
cmd.Parameters.Add(new OracleParameter("num2", num2));
cmd.Parameters.Add(new OracleParameter("mydate", OracleDbType.Date));
cmd.Parameters[3].Value = mydate;
rowid= cmd.ExecuteNonQuery();
myTrans.Commit();
}
}
return rowid;
}

Looks like you're updating rows with their current values. Try adding : to parameter names in the query:
UPDATE CustomObjectS SET num = :num,
mydate=:mydate, num2=:num2, user=:user WHERE num = :num
Using Oracle parameters

Check if a specific row exists, and if it doesn't, add a new one

I'm beginner in SQL and C#. My question is: how do I check whether a row in the table exists or not? Here is my code that I am currently using:
var conn = new SqlConnection(#"Data Source");
conn.Open();
var cmd = new SqlCommand("INSERT INTO Results (PlayerName) VALUES (#PlayerName) " , conn);
cmd.Parameters.Add("#PlayerName",_playerName);
cmd.ExecuteNonQuery();
conn.Close();
I want to check if the player name exists or not, and if not, then add it to the table.

You can check it with Select statement first and then insert it if it is not exist.
Also use using statement to dispose your connection and commands automatically instead of calling Close method manually.
using(var conn = new SqlConnection(yourConnectionString))
using(var cmd = conn.CreateCommand())
{
cmd.CommandText = "Select Count(*) From Results Where PlayerName = #playerName";
cmd.Parameters.Add("#playerName", _playerName);
con.Open();
int count = (int)cmd.ExecuteScalar();
if(count == 0)
{
// It means it does not exist.
cmd.CommandText = "INSERT INTO Results(PlayerName) VALUES (#playerName)";
cmd.ExecuteNonQuery();
}
}

if not exists(select null from Results where PlayerName=#PlayerName) begin INSERT INTO Results (PlayerName) VALUES (#PlayerName) end

How to define a limit as parameter?

Given conn is an OdbcConnection object and count is an int, how would I use count as parameter for my query?
...
var query = conn.CreateCommand();
query.CommandText = "select top ? * from players order by Points desc";
query.Parameters.Add("top", OdbcType.Int).Value = count;
var reader = query.ExecuteReader();
while (reader.Read())
{
...
}
...
This way I get a syntax error ERROR [42000] [Microsoft][ODBC SQL Server Driver][SQL Server]Incorrect syntax near '#P1'.
If it is not possible the way I tried how would I do it the correct way instead?

You can also use SET ROWCOUNT the advantage is you can use a integer as parameter and avoid dynamic queries.
SET ROWCOUNT #top;
select * from table;
SET ROWCOUNT 0;
read the documentation

You can do:
query.CommandText = "select top (#topparameter) * from players order by Points desc";
query.Parameters.AddWithValue("#topparameter", count.ToString());
If you are using SqlServer then use SqlConnection and SqlCommand like:
using (SqlConnection conn = new SqlConnection("YourConnectionString"))
{
using (SqlCommand query = new SqlCommand("select top (#topparameter) * from players order by Points desc", conn))
{
query.Parameters.AddWithValue("#topparameter", count.ToString());
var reader = query.ExecuteReader();
while (reader.Read())
{
}
}
}

Retrieving total count from database to c#

This query is been executed in database.
select COUNT(*) from Patient_Data where DummyValue = 'Y';
104
I have to retrieve this number (104) from database to asp.net with c# so that when the count becomes zero I have to disable a button, How to retrieve this number from database into the code. It should be stored as integer.
I have tried these line of code in c#
using (SqlConnection cn = new SqlConnection(ConfigurationManager.ConnectionStrings["ConStr"].ConnectionString))
{
using (SqlCommand cmd = new SqlCommand("select COUNT(*) as PatientCount from Patient_Data where DummyValue = 'Y' ", cn))
{
try
{
cn.Open();
using (SqlDataReader rdr = cmd.ExecuteReader())
{
int Patcount;
if (rdr.Read())
{
//Code Required
}
}
}
catch (Exception ex)
{
// handle errors here
}
}
}

use alias to get the count as below:
select COUNT(*) as PatientCount from Patient_Data where DummyValue = 'Y';
Read the PatientCount value in code.
you can use GetInt32() function to get the count as int.
Note: you are passing the parameter values in your query which leads to Sql Injection Attacks, so you could use Parameterized Sql Queries to avoid them.
sample code is asbelow:
private int readPatientData()
{
int PatientCount = 0;
String strCommand = "select COUNT(*) as PatientCount from Patient_Data where DummyValue = #MyDummyValue";
using (SqlConnection sqlConnection = new SqlConnection(ConfigurationManager.ConnectionStrings["ConStr"].ConnectionString))
{
sqlConnection.Open();
using (SqlCommand sqlcommand=new SqlCommand(strCommand,sqlConnection))
{
sqlcommand.Parameters.Add(new SqlParameter("MyDummyValue", 'Y'));
SqlDataReader sqlReader = sqlcommand.ExecuteReader();
if (sqlReader.Read())
PatientCount = sqlReader.GetInt32(0);
}
}
return PatientCount;
}

I solved my issue with these lines of code.
using (SqlConnection cn = new SqlConnection(ConfigurationManager.ConnectionStrings["ConStr"].ConnectionString))
{
using (SqlCommand cmd = new SqlCommand("select COUNT(*) as PatientCount from Patient_Data where DummyValue = 'Y' ", cn))
{
try
{
cn.Open();
using (SqlDataReader rdr = cmd.ExecuteReader())
{
//int Patcount;
if (rdr.Read())
{
int Patcount = int.Parse(rdr["PatientCount"].ToString());
if (Patcount != 0)
{
Label3.Visible = true;
Label3.Text = "You have already have "+Patcount+" dummy records,Please update those records by clicking Update Dummy Records Link.";
btnSkipSubmit.Visible = false;
}
//Code Required
}
}
}
catch (Exception ex)
{
// handle errors here
}
}
}

Update based on code change in question
You can write rdr.GetInt32(3); instead of code required in your code.
previous answer
You need to use ExecuteScalar method while executing your command. Here is the example from msdn:
static public int AddProductCategory(string newName, string connString)
{
Int32 newProdID = 0;
string sql =
"INSERT INTO Production.ProductCategory (Name) VALUES (#Name); "
+ "SELECT CAST(scope_identity() AS int)";
using (SqlConnection conn = new SqlConnection(connString))
{
SqlCommand cmd = new SqlCommand(sql, conn);
cmd.Parameters.Add("#Name", SqlDbType.VarChar);
cmd.Parameters["#name"].Value = newName;
try
{
conn.Open();
newProdID = (Int32)cmd.ExecuteScalar();
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
}
return (int)newProdID;
}
In this example they are returning newly added product Id.
ExecuteScalar returns object that you can check for null and cast to number as you know with int.parse method or the best one you know.

As Per my knowledge there are three ways to do this:
Using COUNT you can do this as below:
select COUNT(*) as RowCount from Patient_Data where DummyValue = 'Y';
Using ROW_NUMBER you can do this as below:
Select ROW_NUMBER() OVER (ORDER BY Patient_Data.ID DESC) AS RowNumber from Patient_Data where DummyValue = 'Y';
And there is another way but that way is only to get the row count and is the fastest way to get the row count in sql server according to me.
SELECT
Total_Rows= SUM(st.row_count)
FROM
sys.dm_db_partition_stats st
WHERE
object_name(object_id) = 'Patient_Data' AND (index_id < 2)
That's all

SQL SELECT With Stored Procedure and Parameters?

I've been writing a lot of web services with SQL inserts based on a stored procedure, and I haven't really worked with any SELECTS.
The one SELECT I have in mind is very simple.
SELECT COUNT(AD_SID) As ReturnCount FROM AD_Authorization
WHERE AD_SID = #userSID
However, I can't figure out based on my current INSERT code how to make that into a SELECT and return the value of ReturnCount... Can you help? Here is my INSERT code:
string ConnString = "Data Source=Removed";
string SqlString = "spInsertProgress";
using (OleDbConnection conn = new OleDbConnection(ConnString))
{
using (OleDbCommand cmd = new OleDbCommand(SqlString, conn))
{
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.AddWithValue("attachment_guid", smGuid.ToString());
cmd.Parameters.AddWithValue("attachment_percentcomplete", fileProgress);
conn.Open();
cmd.ExecuteNonQuery();
conn.Close();
}
}

Here is where you are going wrong:
cmd.ExecuteNonQuery();
You are executing a query.
You need to ExecuteReader or ExecuteScalar instead. ExecuteReader is used for a result set (several rows/columns), ExecuteScalar when the query returns a single result (it returns object, so the result needs to be cast to the correct type).
var result = (int)cmd.ExecuteScalar();
The results variable will now hold a OledbDataReader or a value with the results of the SELECT. You can iterate over the results (for a reader), or the scalar value (for a scalar).

Since you are only after a single value, you can use cmd.ExecuteScalar();
A complete example is as follows:
string ConnString = "Data Source=Removed";
string userSid = "SomeSid";
string SqlString = "SELECT COUNT(AD_SID) As ReturnCount FROM AD_Authorization WHERE AD_SID = #userSID;";
int returnCount = 0;
using (OleDbConnection conn = new OleDbConnection(ConnString))
{
using (OleDbCommand cmd = new OleDbCommand(SqlString, conn))
{
cmd.CommandType = CommandType.Text;
cmd.Parameters.AddWithValue("#userSID", userSid);
conn.Open();
returnCount = Convert.ToInt32(cmd.ExecuteScalar());
}
}
If you wanted to return MULTIPLE rows, you can use the ExecuteReader() method. This returns an IDataReader via which you can enumerate the result set row by row.

You need to use ExecuteScalar instead of ExecuteNonQuery:
String query = "SELECT COUNT(AD_SID) As ReturnCount FROM AD_Authorization WHERE AD_SID = #userSID ";
using (OleDbConnection conn = new OleDbConnection(ConnString)) {
using (OleDbCommand cmd = new OleDbCommand(query, conn))
{
cmd.Parameters.AddWithValue("userSID", userSID.ToString());
conn.Open();
int returnCount = (Int32) cmd.ExecuteScalar();
conn.Close();
}
}

cmd.executescalar will return a single value, such as your count.
You would use cmd.executereader when you are returning a list of records