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Can't use InsertOnSubmit method when inserting in database LINQ C#

There's an error when I write this code and says 'object' does not contain a definition for 'InsertOnSubmit' and no extension method like it. Here's my code.
LoginDBDataContext dc = new LoginDBDataContext(conn);
Student_User su = new Student_User();
int user = System.Convert.ToInt32(txtUser.Text);
string pass = txtPassword.Text;
su.Student_Number = user;
su.Password = pass;
su.Lock_Try = 0;
su.Lock_Date = DateTime.Now;
su.Forgot_Password = 0;
dc.Student_User.InsertOnSubmit(su);
dc.SubmitChanges();

replace dc.Student_User.InsertOnSubmit(su); with dc.Student_Users.InsertOnSubmit(su); or wtever your name is for DbSet<Student_User> in your dbModel.
dc.Student_Users.InsertOnSubmit(su);because appending s to entity is normal covention.

Dapper query with dynamic list of filters

I have a c# mvc app using Dapper. There is a list table page which has several optional filters (as well as paging). A user can select (or not) any of several (about 8 right now but could grow) filters, each with a drop down for a from value and to value. So, for example, a user could select category "price" and filter from value "$100" to value "$200". However, I don't know how many categories the user is filtering on before hand and not all of the filter categories are the same type (some int, some decimal/double, some DateTime, though they all come in as string on FilterRange).
I'm trying to build a (relatively) simple yet sustainable Dapper query for this. So far I have this:
public List<PropertySale> GetSales(List<FilterRange> filterRanges, int skip = 0, int take = 0)
{
var skipTake = " order by 1 ASC OFFSET #skip ROWS";
if (take > 0)
skipTake += " FETCH NEXT #take";
var ranges = " WHERE 1 = 1 ";
for(var i = 0; i < filterRanges.Count; i++)
{
ranges += " AND #filterRanges[i].columnName BETWEEN #filterRanges[i].fromValue AND #filterRanges[i].toValue ";
}
using (var conn = OpenConnection())
{
string query = #"Select * from Sales "
+ ranges
+ skipTake;
return conn.Query<Sale>(query, new { filterRanges, skip, take }).AsList();
}
}
I Keep getting an error saying "... filterRanges cannot be used as a parameter value"
Is it possible to even do this in Dapper? All of the IEnumerable examples I see are where in _ which doesn't fit this situation. Any help is appreciated.

You can use DynamicParameters class for generic fields.
Dictionary<string, object> Filters = new Dictionary<string, object>();
Filters.Add("UserName", "admin");
Filters.Add("Email", "admin#admin.com");
var builder = new SqlBuilder();
var select = builder.AddTemplate("select * from SomeTable /**where**/");
var parameter = new DynamicParameters();
foreach (var filter in Filters)
{
parameter.Add(filter.Key, filter.Value);
builder.Where($"{filter.Key} = #{filter.Key}");
}
var searchResult = appCon.Query<ApplicationUser>(select.RawSql, parameter);

You can use a list of dynamic column values but you cannot do this also for the column name other than using string format which can cause a SQL injection.
You have to validate the column names from the list in order to be sure that they really exist before using them in a SQL query.
This is how you can use the list of filterRanges dynamically :
const string sqlTemplate = "SELECT /**select**/ FROM Sale /**where**/ /**orderby**/";
var sqlBuilder = new SqlBuilder();
var template = sqlBuilder.AddTemplate(sqlTemplate);
sqlBuilder.Select("*");
for (var i = 0; i < filterRanges.Count; i++)
{
sqlBuilder.Where($"{filterRanges[i].ColumnName} = #columnValue", new { columnValue = filterRanges[i].FromValue });
}
using (var conn = OpenConnection())
{
return conn.Query<Sale>(template.RawSql, template.Parameters).AsList();
}

You can easily create that dynamic condition using DapperQueryBuilder:
using (var conn = OpenConnection())
{
var query = conn.QueryBuilder($#"
SELECT *
FROM Sales
/**where**/
order by 1 ASC
OFFSET {skip} ROWS FETCH NEXT {take}
");
foreach (var filter in filterRanges)
query.Where($#"{filter.ColumnName:raw} BETWEEN
{filter.FromValue.Value} AND {filter.ToValue.Value}");
return conn.Query<Sale>(query, new { filterRanges, skip, take }).AsList();
}
Or without the magic word /**where**/:
using (var conn = OpenConnection())
{
var query = conn.QueryBuilder($#"
SELECT *
FROM Sales
WHERE 1=1
");
foreach (var filter in filterRanges)
query.Append($#"{filter.ColumnName:raw} BETWEEN
{filter.FromValue.Value} AND {filter.ToValue.Value}");
query.Append($"order by 1 ASC OFFSET {skip} ROWS FETCH NEXT {take}");
return conn.Query<Sale>(query, new { filterRanges, skip, take }).AsList();
}
The output is fully parametrized SQL, even though it looks like we're doing plain string concatenation.
Disclaimer: I'm one of the authors of this library

I was able to find a solution for this. The key was to convert the List to a Dictionary. I created a private method:
private Dictionary<string, object> CreateParametersDictionary(List<FilterRange> filters, int skip = 0, int take = 0)
{
var dict = new Dictionary<string, object>()
{
{ "#skip", skip },
{ "#take", take },
};
for (var i = 0; i < filters.Count; i++)
{
dict.Add($"column_{i}", filters[i].Filter.Description);
// some logic here which determines how you parse
// I used a switch, not shown here for brevity
dict.Add($"#fromVal_{i}", int.Parse(filters[i].FromValue.Value));
dict.Add($"#toVal_{i}", int.Parse(filters[i].ToValue.Value));
}
return dict;
}
Then to build my query,
var ranges = " WHERE 1 = 1 ";
for(var i = 0; i < filterRanges.Count; i++)
ranges += $" AND {filter[$"column_{i}"]} BETWEEN #fromVal_{i} AND #toVal_{i} ";
Special note: Be very careful here as the column name is not a parameter and you could open your self up to injection attacks (as #Popa noted in his answer). In my case those values come from an enum class and not from user in put so I am safe.
The rest is pretty straight forwared:
using (var conn = OpenConnection())
{
string query = #"Select * from Sales "
+ ranges
+ skipTake;
return conn.Query<Sale>(query, filter).AsList();
}

IBM db2Command SQL SELECT * FROM IN #namedParameter

When using the C# code below to construct a DB2 SQL query the result set only has one row. If I manually construct the "IN" predicate inside the cmdTxt string using string.Join(",", ids) then all of the expected rows are returned. How can I return all of the expected rows using the db2Parameter object instead of building the query as a long string to be sent to the server?
public object[] GetResults(int[] ids)
{
var cmdTxt = "SELECT DISTINCT ID,COL2,COL3 FROM TABLE WHERE ID IN ( #ids ) ";
var db2Command = _DB2Connection.CreateCommand();
db2Command.CommandText = cmdTxt;
var db2Parameter = db2Command.CreateParameter();
db2Parameter.ArrayLength = ids.Length;
db2Parameter.DB2Type = DB2Type.DynArray;
db2Parameter.ParameterName = "#ids";
db2Parameter.Value = ids;
db2Command.Parameters.Add(db2Parameter);
var results = ExecuteQuery(db2Command);
return results.ToArray();
}
private object[] ExecuteQuery(DB2Command db2Command)
{
_DB2Connection.Open();
var resultList = new ArrayList();
var results = db2Command.ExecuteReader();
while (results.Read())
{
var values = new object[results.FieldCount];
results.GetValues(values);
resultList.Add(values);
}
results.Close();
_DB2Connection.Close();
return resultList.ToArray();
}

You cannot send in an array as a parameter. You would have to do something to build out a list of parameters, one for each of your values.
e.g.: SELECT DISTINCT ID,COL2,COL3 FROM TABLE WHERE ID IN ( #id1, #id2, ... #idN )
And then add the values to your parameter collection:
cmd.Parameters.Add("#id1", DB2Type.Integer).Value = your_val;
Additionally, there are a few things I would do to improve your code:
Use using statements around your DB2 objects. This will automatically dispose of the objects correctly when they go out of scope. If you don't do this, eventually you will run into errors. This should be done on DB2Connection, DB2Command, DB2Transaction, and DB2Reader objects especially.
I would recommend that you wrap queries in a transaction object, even for selects. With DB2 (and my experience is with z/OS mainframe, here... it might be different for AS/400), it writes one "accounting" record (basically the work that DB2 did) for each transaction. If you don't have an explicit transaction, DB2 will create one for you, and automatically commit after every statement, which adds up to a lot of backend records that could be combined.
My personal opinion would also be to create a .NET class to hold the data that you are getting back from the database. That would make it easier to work with using IntelliSense, among other things (because you would be able to auto-complete the property name, and .NET would know the type of the object). Right now, with the array of objects, if your column order or data type changes, it may be difficult to find/debug those usages throughout your code.
I've included a version of your code that I re-wrote that has some of these changes in it:
public List<ReturnClass> GetResults(int[] ids)
{
using (var conn = new DB2Connection())
{
conn.Open();
using (var trans = conn.BeginTransaction(IsolationLevel.ReadCommitted))
using (var cmd = conn.CreateCommand())
{
cmd.Transaction = trans;
var parms = new List<string>();
var idCount = 0;
foreach (var id in ids)
{
var parm = "#id" + idCount++;
parms.Add(parm);
cmd.Parameters.Add(parm, DB2Type.Integer).Value = id;
}
cmd.CommandText = "SELECT DISTINCT ID,COL2,COL3 FROM TABLE WHERE ID IN ( " + string.Join(",", parms) + " ) ";
var resultList = new List<ReturnClass>();
using (var reader = cmd.ExecuteReader())
{
while (reader.Read())
{
var values = new ReturnClass();
values.Id = (int)reader["ID"];
values.Col1 = reader["COL1"].ToString();
values.Col2 = reader["COL2"].ToString();
resultList.Add(values);
}
}
return resultList;
}
}
}
public class ReturnClass
{
public int Id;
public string Col1;
public string Col2;
}

Try changing from:
db2Parameter.DB2Type = DB2Type.DynArray;
to:
db2Parameter.DB2Type = DB2Type.Integer;
This is based on the example given here

Parameterize DocumentDB query with IN clause

I have a query somewhat like the following which I'm trying to parameterize:
List<string> poiIDs = /*List of poi ids*/;
List<string> parameterNames = /*List of parameter names*/;
string inClause = string.Join(",", parameterNames);
string query = string.Format("SELECT c.id AS poiID, c.poiName, c.latitude, c.longitude FROM c WHERE c.clusterName = #clusterName AND c.id IN ({0}) AND c.deleted = false", inClause);
IQueryable<POI> queryResult = Client.CreateDocumentQuery<POI>(Collection.SelfLink, new SqlQuerySpec
{
QueryText = query,
Parameters = new SqlParameterCollection()
{
new SqlParameter("#clusterName", "POI"),
// How do I declare the dynamically generated parameters here
// as new SqlParameter()?
}
});
How do I declare the dynamically generated parameters as new SqlParameter() for the Parameters property of SqlQuerySpec in order to create my document query?

You can create dynamic parameterized query like this:
// DocumentDB query
// POINT TO PONDER: create the formatted query, so that after creating the dynamic query we'll replace it with dynamically created "SQL Parameter/s"
var queryText = #"SELECT
us.id,
us.email,
us.status,
us.role
FROM user us
WHERE us.status = #userStatus AND us.email IN ({0})";
// contain's list of emails
IList<string> emailIds = new List<string>();
emailIds.Add("a#gmail.com");
emailIds.Add("b#gmail.com");
#region Prepare the query
// simple parameter: e.g. check the user status
var userStatus = "active";
var sqlParameterCollection = new SqlParameterCollection { new SqlParameter("#userStatus", userStatus) };
// IN clause: with list of parameters:
// first: use a list (or array) of string, to keep the names of parameter
// second: loop through the list of input parameters ()
var namedParameters = new List<string>();
var loopIndex = 0;
foreach (var email in emailIds)
{
var paramName = "#namedParam_" + loopIndex;
namedParameters.Add(paramName);
var newSqlParamter = new SqlParameter(paramName, email);
sqlParameterCollection.Add(newSqlParamter);
loopIndex++;
}
// now format the query, pass the list of parameter into that
if (namedParameters.Count > 0)
queryText = string.Format(queryText, string.Join(" , ", namedParameters));
// after this step your query is something like this
// SELECT
// us.id,
// us.email,
// us.status,
// us.role
// FROM user us
// WHERE us.status = #userStatus AND us.email IN (#namedParam_0, #namedParam_1, #namedParam_2)
#endregion //Prepare the query
// now inject the parameter collection object & query
var users = Client.CreateDocumentQuery<Users>(CollectionUri, new SqlQuerySpec
{
QueryText = queryText,
Parameters = sqlParameterCollection
}).ToList();

The following gives you a SQL query, you can then run in your DocumentDB Collection, to get the Documents by their IDs.
var query = $"SELECT * FROM p WHERE p.id IN ('{string.Join("', '", arrayOfIds)}')";

The DocumentDB SDK doesn't support parameterized IN queries.
Judging from the SO thread in the comment above, SQL does not either. As mentioned in the other thread, you can use LINQ as a workaround.

Why not use the ArrayContains method? Here is an example in node
sqlQuery = {
query: 'SELECT * FROM t WHERE ARRAY_CONTAINS(#idList, t.id)',
parameters: [
{
name: '#idList',
value: ['id1','id2','id3'],
},
],
};

Convert Function Based on TSQL with Function Based with Entity Framework

I have two functions that each return the same list of objects. But, the one that uses TSQL is much faster than the one using Entity Framework and I do not understand why one would be faster than the other. Is it possible to modify my EF function to work as fast as the TSQL one?
Any help will be appreciated. My code is below:
TSQL:
public static List<ChartHist> ListHistory_PureSQL()
{
List<DataRow> listDataRow = null;
string srtQry = #"Select LoginHistoryID,
LoginDuration as LoginDuration_Pass,
0 as LoginDuration_Fail,
LoginDateTime,
LoginLocationID,
LoginUserEmailID,
LoginApplicationID,
LoginEnvironmentID,
ScriptFrequency,
LoginStatus,
Reason
From LoginHistory
Where LoginStatus = 'Pass'
UNION
Select LoginHistoryID,
0 as LoginDuration_Pass,
LoginDuration as LoginDuration_Fail,
LoginDateTime,
LoginLocationID,
LoginUserEmailID,
LoginApplicationID,
LoginEnvironmentID,
ScriptFrequency,
LoginStatus,
Reason
From LoginHistory
Where LoginStatus = 'Fail'";
using (SqlConnection conn = new SqlConnection(Settings.ConnectionString))
{
using (SqlCommand objCommand = new SqlCommand(srtQry, conn))
{
objCommand.CommandType = CommandType.Text;
DataTable dt = new DataTable();
SqlDataAdapter adp = new SqlDataAdapter(objCommand);
conn.Open();
adp.Fill(dt);
if (dt != null)
{
listDataRow = dt.AsEnumerable().ToList();
}
}
}
var listChartHist = (from p in listDataRow
select new ChartHist
{
LoginHistoryID = p.Field<Int32>("LoginHistoryID"),
LoginDuration_Pass = p.Field<Int32>("LoginDuration_Pass"),
LoginDuration_Fail = p.Field<Int32>("LoginDuration_Fail"),
LoginDateTime = p.Field<DateTime>("LoginDateTime"),
LoginLocationID = p.Field<Int32>("LoginLocationID"),
LoginUserEmailID = p.Field<Int32>("LoginUserEmailID"),
LoginApplicationID = p.Field<Int32>("LoginApplicationID"),
LoginEnvironmentID = p.Field<Int32>("LoginEnvironmentID"),
ScriptFrequency = p.Field<Int32>("ScriptFrequency"),
LoginStatus = p.Field<String>("LoginStatus"),
Reason = p.Field<String>("Reason")
}).ToList();
return listChartHist;
}
EF:
public static List<ChartHist> ListHistory()
{
using (var db = new LatencyDBContext())
{
var loginHist = (from hist in db.LoginHistories
select new { LoginHistory = hist }).ToList();
//PUT LOGIN HISTORY RECORDS INTO A LOCAL LIST
var listHistory = new List<ChartHist>();
foreach (var item in loginHist)
{
var localHistData = new ChartHist();
localHistData.LoginHistoryID = item.LoginHistory.LoginHistoryID;
//split up the duration for pass and fail values
if (item.LoginHistory.LoginStatus.ToUpper() == "PASS")
{
localHistData.LoginDuration_Pass = Convert.ToDouble(item.LoginHistory.LoginDuration);
localHistData.LoginDuration_Fail = 0;
}
else if (item.LoginHistory.LoginStatus.ToUpper() == "FAIL")
{
localHistData.LoginDuration_Pass = 0;
localHistData.LoginDuration_Fail = Convert.ToDouble(item.LoginHistory.LoginDuration);
}
localHistData.LoginDateTime = item.LoginHistory.LoginDateTime;
localHistData.LoginLocationID = item.LoginHistory.LoginLocationID;
localHistData.LoginUserEmailID = item.LoginHistory.LoginUserEmailID;
localHistData.LoginApplicationID = item.LoginHistory.LoginApplicationID;
localHistData.LoginEnvironmentID = item.LoginHistory.LoginEnvironmentID;
localHistData.LoginStatus = item.LoginHistory.LoginStatus;
localHistData.Reason = item.LoginHistory.Reason;
localHistData.ScriptFrequency = item.LoginHistory.ScriptFrequency;
listHistory.Add(localHistData);
}
return listHistory;
}
}

Of course EF will take longer to execute than a plain old SQL query, and there's very little that you can do about it (except write the most optimal LINQ queries that you can).
There's a very simple reason why this is so. Running a direct SQL command will just send back the data, with no muss and no fuss attached to it, waiting for you to do the data manipulations to get it to the point where it fits nicely into whatever data structure you want it in. Running EF, on the other hand, means that not only does it run the SQL command, but it massages the data for you into objects that you can manipulate right away. That extra action of going through ADO.NET and converting the data into the objects automatically means that it will take longer than just doing the plain SQL query.
On the flip side of that coin, however, EF does provide a very nice and simple way to debug and solve whatever problems you might have from a specific query/function (like by any exceptions thrown).

I can't performance test this, but try this solution instead before you remove EF entirely:
var loginHist = db.LoginHistories.Where(item => item.LoginStatus.ToUpper() == "PASS" || item.LoginStatus.ToUpper() == "FAIL")
.Select(item => new ChartHist()
{
LoginHistoryID = item.LoginHistoryID,
LoginDuration_Pass = item.LoginStatus.ToUpper() == "PASS" ? Convert.ToDouble(item.LoginDuration) : 0,
LoginDuration_Fail = item.LoginStatus.ToUpper() == "FAIL" ? Convert.ToDouble(item.LoginDuration) : 0,
LoginDateTime = item.LoginDateTime,
LoginLocationID = item.LoginLocationID,
LoginUserEmailID = item.LoginUserEmailID,
LoginApplicationID = item.LoginApplicationID,
LoginEnvironmentID = item.LoginEnvironmentID,
LoginStatus = item.LoginStatus,
Reason = item.Reason,
ScriptFrequency = item.ScriptFrequency,
});
return loginHist.ToList();
This is the "correct" way to populate a new object from a select. It will only retrieve the data you care about, and will put it directly into the object, rather than converting it into an object and then converting it again, from one object to another.
Note: I prefer the functional calls to the from / select form, but it'd be correct either way.