newbie: why does DataSet AutoIncrement advance by 2?

[deko]

I create a DataSet called database and add a table to it as shown below.
Why does the AutoIncrement value advance by 2 every time I add a record?
How do I get it to advance by 1?

DataTable tblProject = database.Tables.Add("TableProject");
DataColumn project_ID = tblProject.Columns.Add("Project_ID", typeof(Int32));
project_ID.AllowDBNull = false;
project_ID.Unique = true;
project_ID.AutoIncrement = true;
project_ID.AutoIncrementSeed = 1;
project_ID.AutoIncrementStep = 1;
tblProject.PrimaryKey = new DataColumn[] { tblProject.Columns[0] };

//other columns added here...

 

[Miha Markic [MVP C#]]

Hi,

You should use negative values for Auto*. This way they won't interfere with
database generated values and you can immediately spot new row.
project_ID.AutoIncrementSeed = -1;
project_ID.AutoIncrementStep = -1;

 

[Patrice]

And make sure you don't do call NewRow twice...
--

Hi,

You should use negative values for Auto*. This way they won't interfere with
database generated values and you can immediately spot new row.
project_ID.AutoIncrementSeed = -1;
project_ID.AutoIncrementStep = -1;


--
Miha Markic [MVP C#]
RightHand .NET consulting & development www.rthand.com
Blog: http://cs.rthand.com/blogs/blog_with_righthand/

I create a DataSet called database and add a table to it as shown below.
Why does the AutoIncrement value advance by 2 every time I add a record?
How do I get it to advance by 1?

DataTable tblProject = database.Tables.Add("TableProject");
DataColumn project_ID = tblProject.Columns.Add("Project_ID",
typeof(Int32));
project_ID.AllowDBNull = false;
project_ID.Unique = true;
project_ID.AutoIncrement = true;
project_ID.AutoIncrementSeed = 1;
project_ID.AutoIncrementStep = 1;
tblProject.PrimaryKey = new DataColumn[] { tblProject.Columns[0] };

//other columns added here...

 

[deko]

You should use negative values for Auto*. This way they won't interfere

with database generated values and you can immediately spot new row.
project_ID.AutoIncrementSeed = -1;
project_ID.AutoIncrementStep = -1;

Thanks for the tip.

But what database generated code?

 

[deko]

And make sure you don't do call NewRow twice...

Here's how I add a row:

public int insertNewProject(string projectName)
{
dtP = database.Tables[tblP]; //tblP is a string const
int rowCount = dtP.Rows.Count;
Console.WriteLine(rowCount);
foreach (DataRow row in dtP.Rows)
{
Console.WriteLine(row[colPid]); //colP is a string const
}
DataRow newRow = dtP.NewRow();
Console.WriteLine(projectName);
newRow[colP] = projectName;
dtP.Rows.Add();
database.AcceptChanges();
DataRow lastRow = dtP.Rows[rowCount];
int pid = (int)lastRow[colPid]; //I want to get the ID of the newly added
row
return pid;
}

The AutoNumber PK still increments by 2 with the negative value, and
projectName never makes it into the table for some reason.

 

[Patrice]

dtP.Rows.Add();

Never used this. It's likely adding a blank row. Try dtp.Rows.Add(newRow);
instead to add the row you previoulsy initialized rather than IMO a new
blank one...

--
Patrice

And make sure you don't do call NewRow twice...

Here's how I add a row:

public int insertNewProject(string projectName)
{
dtP = database.Tables[tblP]; //tblP is a string const
int rowCount = dtP.Rows.Count;
Console.WriteLine(rowCount);
foreach (DataRow row in dtP.Rows)
{
Console.WriteLine(row[colPid]); //colP is a string const
}
DataRow newRow = dtP.NewRow();
Console.WriteLine(projectName);
newRow[colP] = projectName;
dtP.Rows.Add();
database.AcceptChanges();
DataRow lastRow = dtP.Rows[rowCount];
int pid = (int)lastRow[colPid]; //I want to get the ID of the newly added
row
return pid;
}

The AutoNumber PK still increments by 2 with the negative value, and
projectName never makes it into the table for some reason.

 

[Guest]

deko,

Database generated VALUES. The database is going to generate autonumber
primary key values when you update the database with new rows from the
dataset.

Kerry Moorman

 

[deko]

dtP.Rows.Add();

Never used this. It's likely adding a blank row. Try dtp.Rows.Add(newRow);
instead to add the row you previoulsy initialized rather than IMO a new
blank one...

You are 100% correct.

This also fixed the AutoIncrement double advance:

dtP.Rows.Add(newRow);

Thanks for the help!

 

[deko]

Database generated VALUES. The database is going to generate autonumber

primary key values when you update the database with new rows from the
dataset.

10-4. But it was said (at least I think it was said) that it's better to
step the AutoIncrement PK with -1 so it does not conflict with database
generated values. My question was WHAT database-generated values? Are we
talking about other AutoIncrement columns?

I could have a dozen AutoIncrement fields in the same table - there is no
conflict there.

Is stepping with -1 just a preference?