A DataReader reads a forward-only stream of rows from a data source.
A DataReader reads a forward-only stream of rows from a data source. This tag is for questions about creating or using a datareader in code.
Questions tagged [datareader]
782 questions
15
votes
1 answer
Handle NULL values when reading through OracleDataReader?
I'm working on my first ASP.Net application, and seem to be hitting a lot of hurdles (background primarily in WinForms with a recent MVC5 project under my belt).
I am successfully making my DB connection using OracleCommand and executing my query,…
Analytic Lunatic
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14
votes
2 answers
DataReader.GetString() via columnname
Dictionary Fields = new Dictionary();
for (int i = 0; i < reader.FieldCount; i++)
{
Fields.Add(reader.GetName(i), i);
}
this._MyField1 = reader.GetString(Fields["field1"]);
this._Myfield2 = reader.GetInt16(Fields["field2"]);
doing this makes…
KellCOMnet
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13
votes
1 answer
DataReader[i] vs DataReader.GetValue(i) vs DataReader.GetString(i)
Is
dataReader[i]
logically equivalent to
dataReader.GetValue(i)
Are they the same? Are they different? Is there a situation where one would be appropriate over the other?
There are documented differently:
Gets the column located at the specified…
Ian Boyd
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13
votes
3 answers
WinRT No mapping for the Unicode character exists in the target multi-byte code page
I am trying to read a file in my Windows 8 Store App. Here is a fragment of code I use to achieve this:
if(file != null)
{
var stream = await file.OpenAsync(FileAccessMode.Read);
var size = stream.Size;
…
Jarek Mazur
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12
votes
2 answers
Generic Relational to Composite C# Object Mapper
I have following code that's capable of mapping Reader to simple objects. The trouble is in case the object is composite it fails to map. I am not able to perform recursion by checking the property if it is a class itself
prop.PropertyType.IsClass
…
Abdul Khan
- 363
- 3
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11
votes
4 answers
Exception of type 'System.OutOfMemoryException' was thrown. C# when using IDataReader
I have an application in which I have to get a large amount of data from DB.
Since it failed to get all of those rows (it's close to 2,000,000 rows...), I cut it in breaks, and I run each time the sql query and get only 200,000 rows each time.
I use…
DA_Prog
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10
votes
5 answers
Using ASP.NET MVC without an ORM
In my ASP MVC application I'm using standard SQL (rather that Linq to SQL or other ORM) to query my database.
I would like to pass the database results to my view and iterate over the results in my view. But I'm not sure how to do this. Every…
CoolGravatar
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10
votes
1 answer
Dapper handling returned empty result set
We are using Dapper to map our sql data and so far it has worked very well. I have a case though where we are doing something similar to:
someObject = con.Query("GetInfoSproc", p, commandType: CommandType.StoredProcedure).Single();
This works…
John Ten Cate
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10
votes
5 answers
IDataReader - Any way to get the total rows?
Is there any way to get the total number of rows returned from a SQL query (from the IDataReader) before iterating through the rows by using reader.Read();?
michael
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10
votes
1 answer
Output parameters not readable when used with a DataReader
When using a DataReader object to access data from a database (such as SQL Server) through stored procedures, any output parameter added to the Command object before executing are not being filled after reading. I can read row data just fine, as…
Sean Hanley
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9
votes
9 answers
Is datareader quicker than dataset when populating a datatable?
Which would be quicker.
1) Looping a datareader and creating a custom rows and columns based populated datatable
2) Or creating a dataAdapter object and just (.Fill)ing a datatable.
Does the performance of a datareader still hold true upon dynamic…
Squiggs.
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9
votes
2 answers
how can i loop through all of the columns of the OracleDataReader
I have the following code and i want to loop through all the fields in the result of this query and populate the dictionary called field.
Given a datareader is this possible?
OracleCommand command = connection.CreateCommand();
…
leora
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9
votes
4 answers
Can I create an anonymous type collection from a DataReader?
I have this code:
var query = "SELECT * FROM Cats";
var conn = new SqlConnection(sqlConnectionString);
conn.Open();
var cmd = new SqlCommand(query);
var reader = cmd.ExecuteReader();
while (reader.Read())
{
var CatName =…
NibblyPig
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9
votes
2 answers
DataReader best-practices
Similar to this question, but the answers never really got around to what I want to know. Is there any standards around getting values from a DataReader? I.e., is this
dataReader.GetString(dataReader.GetOrdinal("ColumnName"));
considered…
AJ.
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8
votes
4 answers
There is already an open DataReader associated with this Command which must be closed first
This is the code I have.
///
/// Method calls stored procedure and fills DataSet of contacts associated with Lead
///
/// The ID associated with a Lead
/// contacts list as…
Marcus3329
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