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Column abc does not belong to table?

I am iterating a DataTable in my C# code. I try to get the contents using of a column named "columnName" of row named "row" using -
object value = row["ColumnName"];
I get this error -
Error: System.Reflection.TargetInvocationException: Exception has been
thrown by the target of an invocation.
---> System.ArgumentException: Column 'FULL_COUNT' does not belong to table . at System.Data.DataRow.GetDataColumn(String columnName)
How is this possible ? My SQL query/result set has a column by that name and the query even runs in management studio.
How do I fix this error ?

I am guessing your code is iteration supposed to be something like this
DataTable table = new DataTable();
foreach (DataRow row in table.Rows) {
foreach (DataColumn col in table.Columns) {
object value = row[col.ColumnName];
}
}
If this is the case, row["ColumnName"] in each iteration looks for the same column with name ColumnName which obviously does not exists in your table.
The correct way is row[ColumnName] or row[col.ColumnName] in iteration above

I had a similar issue on my c# code, using a dataset which I had successfully initialized and populated with data from the DB.
So my return set was:
data = new Byte[0];
data = (Byte[])(dataset.Tables[0].Rows[0]["systemLogo_img"]);
Of course the error was in t finding the column 'systemLogo_img'.
I noted that you simply do NOT have to call /qualify the column name. So the correction is:
data = new Byte[0];
data = (Byte[])(dataset.Tables[0].Rows[0].ItemArray[0]);
Simply put: use "ItemArray" at position.
Thanks

Do not write Gridview column names instead of Database column names.
dataGridViewEmployeeClass.Rows[n].Cells[0].Value = item["write the Database Column names"].ToString();

Try this, make sure your column name is same
DataTable dt = new DataTable();
dt.Columns.Add("abc", typeof(string));
DataRow dr = dt.NewRow();
dr["abc"]="";

I had a similar issue which was very basic to fix.
I was querying with a specific column name rather than Select * (i.e. Select Title). Beginner's error but happens to everyone.

If you want to check if the column exists in the DataRow before accessing the value the following block can help...
if (dataRow.Table.Columns.Contains("theColumnName"))
{
// do work
string text = string.Empty;
if (dataRow["theColumnName"] != System.DBNull.Value)
{
text = Convert.ToString(dataRow["theColumnName"]);
}
}
If it doesn't exist and it needs to be added to the data table you can add the column using #Karthick Ganesan's example
// add a column
dataTable.Columns.Add("theColumnName", typeof(string));

I had same issue was trying to pass two different keys for same product.
item.Product = SqlHelper.GetSafeString(dr, "ProductName");
item.Product = SqlHelper.GetSafeString(dr, "Product");

C#: How can I select specific rows from the ResultsTable returned from a KeywordQuery?

I am trying to perform a two-pass search against a Sharepoint list. In the first pass, I am using a KeywordQuery to search against the index of all the items. In the second pass, I am applying column value filters chosen by a user by building a select statement.
ResultTableCollection rtc = kwqry.Execute();
ResultTable rt = rtc[ResultType.RelevantResults];
dt = new DataTable();
//Load Data Table
dt.Load(rt, LoadOption.OverwriteChanges);
DataRow[] rows = dt.Select("ColumnName1 = 'foo' AND ColumnName2 = 'bar'");
Where the columns could be multi-value lookup columns in a Sharepoint list. The first pass is working properly and returning the right number of matches in a DataTable. However, when I try to apply the Select statement, I get the following error: Cannot perform '=' operation on System.String[] and System.String. Converting the columns to a string instead of a string array results in the same error, as does using the IN operator.
Am I building my select statement incorrectly? How could I run my second pass filter on my DataTable?

Have you tried with LINQ?
DataTable t1 = new DataTable();
var rows = from x in t1.AsEnumerable()
where x.Field<string[]>("column1name").Contains("foo")
select x;
You have to specify the field type in the Where clause...
Hope it helps.

Try using this, it will work :
DataRow[] rows = dt.Select("(ColumnName1 = 'foo' AND ColumnName2 = 'bar')");

How to copy all the rows in a datatable to a datarow array?

I have two tables:
tbl_ClassFac:
ClassFacNo (Primary Key)
,FacultyID
,ClassID
tbl_EmpClassFac:
EmpID, (Primary Key)
DateImplement, (Primary Key)
ClassFacNo
I want to know all the Employees who are on a specific ClassFacNo. ie. All EmpID with a specific ClassFacNo... What I do is that I first search tbl_EmpClassFac with the EmpID supplied by the user. I store these datarows. Then use the ClassFacNo from these datarows to search through tbl_ClassFac.
The following is my code.
empRowsCF = ClassFacDS.Tables["EmpClassFac"].Select("EmpID='" + txt_SearchValueCF.Text + "'");
int maxempRowsCF = empRowsCF.Length;
if (maxempRowsCF > 0)
{
foundempDT = ClassFacDS.Tables["ClassFac"].Clone();
foreach (DataRow dRow in empRowsCF)
{
returnedRowsCF = ClassFacDS.Tables["ClassFac"].Select("ClassFacNo='" + dRow[2].ToString() + "'");
foundempDT.ImportRow(returnedRowsCF[0]);
}
}
dataGrid_CF.DataSource = null;
dataGrid_CF.DataSource = foundempDT.DefaultView;
***returnedRowsCF = foundempDT.Rows;*** // so NavigateRecordsCF can be used
NavigateRecordsCF("F"); // function to display data in textboxes (no importance here)
I know the code is not very good but that is all I can think of. If anyone has any suggestions please please tell me. If not tell me how do I copy all the Rows in a datatable to a datarow array ???

"How to copy all the rows in a datatable to a datarow array?"
If that helps, use the overload of Select without a parameter
DataRow[] rows = table.Select();
DataTable.Select()
Gets an array of all DataRow objects.
According to the rest of your question: it's actually not clear what's the question.
But i assume you want to filter the first table by a value of a field in the second(related) table. You can use this concise Linq-To-DataSet query:
var rows = from cfrow in tbl_ClassFac.AsEnumerable()
join ecfRow in tbl_EmpClassFac.AsEnumerable()
on cfrow.Field<int>("ClassFacNo") equals ecfRow.Field<int>("ClassFacNo")
where ecfRow.Field<int>("EmpId") == EmpId
select cfrow;
// if you want a new DataTable from the filtered tbl_ClassFac-DataRows:
var tblResult = rows.CopyToDataTable();
Note that you can get an exception at CopyToDataTable if the sequence of datarows is empty, so the filter didn't return any rows. You can avoid it in this way:
var tblResult = rows.Any() ? rows.CopyToDataTable() : tbl_ClassFac.Clone(); // empty table with same columns as source table

C# - Getting record from a row using DataRow

I'm trying to get record of a row using DataRow. Here's what I've done so far:
uID = int.Parse(Request.QueryString["id"]);
PhotoDataSetTableAdapters.MembersTableAdapter mem = new PhotoDataSetTableAdapters.MembersTableAdapter();
PhotoDataSet.MembersDataTable memTable = mem.GetMemberByID(uID);
DataRow[] dr = memTable.Select("userID = uID");
string uName = dr["username"].ToString();
Then I got the error:
Cannot implicitly convert type 'string' to 'int'
The error points to "username". I don't know what's wrong because I'm just trying to assign a string variable to a string value. Anyone figures out the reason of the error? Please help and thanks.

Change the following statement
DataRow[] dr = memTable.Select("userID = uID");
To
DataRow[] dr = memTable.Select("userID = "+ uID);

dr is a DataRow[] not a DataRow, therefor the compiler complains that you pass a String when he needs an int for the index.
You actually want the username of the the single DataRow in the DataTable, am i right?
String uName = memTable.AsEnumerable().Single().Field<String>("username");
Note that this throws an exception if there is more than one row in the DataTable. But since you pass an ID to the DataAdapter, i assume that it should return only one record.

Seems there are two problems. One is as Asif suggest that uID should be "userId = " + uID (should probably cast uID as string) and that dr is an array of datarows as Tim points out. You can access it by index too: dr[0]["userName"].ToString()

DataTable find or if not found insert row

I have a DataTable dt with 2 columns. First col (call it CustomerId) is unique and doesn't allow nulls. the second one allows nulls and is not unique.
From a method I get a CustomerId and then I would like to either insert a new record if this CustomerId doesn't exist or increment by 1 what's in the second column corresponding to that CustomerId if it exists.
I'm not sure how I should approach this. I wrote a select statement (which returns System.Data.DataRow) but I don't know how to test whether it returned an empty string.
Currently I have:
//I want to insert a new row
if (dt.Select("CustomerId ='" + customerId + "'") == null) //Always true :|
{
DataRow dr = dt.NewRow();
dr["CustomerId"] = customerId;
}

If the datatable is being populated by a database. I would recommend making the customerid a identity column. That way when you add a new row it will automatically create a new customerid which will be unique and 1 greater than the previous id (depending on how you setup your identity column)
I would check the row count which is returned from the select statement. Something like
I would also use string.Format...
So it would look like this
var selectStatement = string.Format("CustomerId = {0}", customerId);
var rows = dt.Select(selectStatement);
if (rows.Count < 1){
var dr = dt.NewRow();
dr["CustomerId"] = customerId;
}

This is my method to solve similar problem. You can modify it to fit your needs.
public static bool ImportRowIfNotExists(DataTable dataTable, DataRow dataRow, string keyColumnName)
{
string selectStatement = string.Format("{0} = '{1}'", keyColumnName, dataRow[keyColumnName]);
DataRow[] rows = dataTable.Select(selectStatement);
if (rows.Length == 0)
{
dataTable.ImportRow(dataRow);
return true;
}
else
{
return false;
}
}

The Select Method returns an array of DataRow objects. Just check if its length is zero (it's never null).
By the way, don't write such statements in the code directly as in this example. There's a technique for breaching your code's security called "SQL Injection", I encourage you to read the Wikipedia Article. In brief, an experienced user could write SQL script that gets executed by your database and potentially do harmful things if you're taking customerId from the user as a string. I'm not experienced in database programming, this is just "general knowledge"...