Variable creation inside an OracleDataReader in C#

Question

It's been helpfully suggested that I don't have to keep writing

dr["building_id"].ToString()

in the code snipped below. That I only need to put the above into a variable, i.e, sBldgID, and use the latter subsequently.

...
using (OracleCommand cmd = new OracleCommand(sql, conn)) {
   cmd.CommandType = CommandType.Text;
   using (OracleDataReader dr = cmd.ExecuteReader()) {
      while (dr.Read()) {
         if (dr["building_id"].ToString() != " " && dr["building_id"].ToString() != "" && dr["building_id"].ToString() != null) {
            using (SpreadsheetDocument document = SpreadsheetDocument.Open(path, true)) {
               IEnumerable<Sheet> sheets = document.WorkbookPart.Workbook.Descendants<Sheet>().Where(s => s.Name == dr["building_id"].ToString());
               WorksheetPart worksheetPart = (WorksheetPart)document.WorkbookPart.GetPartById(sheets.FirstOrDefault().Id);

...
            }
         }
      }
   }
}
...

Good advice. How do I do it? How do I use dr.Read() that way before the while loop starts? Thanks.

René Vogt · Accepted Answer · 2018-07-12 15:40:40Z

1

I guess the advice was pretty clear:

using (OracleCommand cmd = new OracleCommand(sql, conn)) {
   cmd.CommandType = CommandType.Text;
   using (OracleDataReader dr = cmd.ExecuteReader()) {
      while (dr.Read()) {

         string buildingId = dr["building_id"].ToString(); // <-- chache building id

         if (buildingId != " " && buildingId != "" && buildingId != null) {
            using (SpreadsheetDocument document = SpreadsheetDocument.Open(path, true)) {
               IEnumerable<Sheet> sheets = document.WorkbookPart.Workbook.Descendants<Sheet>().Where(s => s.Name == buildingId);
               WorksheetPart worksheetPart = (WorksheetPart)document.WorkbookPart.GetPartById(sheets.FirstOrDefault().Id);

...
            }
         }
      }
   }
}

Simply chache the dr["building_id"].ToString() in a local variable (like building_id here).

edited Jul 12, 2018 at 15:40

answered Jul 12, 2018 at 15:39

René Vogt

44.1k15 gold badges84 silver badges106 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

ni37osllb Over a year ago

Doesn't even that itself keep getting performed every time it loops? Or is that pretty much the shortest route?

René Vogt Over a year ago

@ni37osllb yes of course...every dr.Read() switches to the next row in the result, and I assume you want to use the building_id of this next row. Or is this building id the same in all rows?

derpirscher Over a year ago

For better readability I suggest using if (!String.IsNullOrWhiteSpace(buildingId)) instead of 3 comparisons.

René Vogt Over a year ago

@derpirscher I'd agree, but don't know OP's detailed requirements, maybe it's not the same

ni37osllb Over a year ago

René, building_id is different for other rows, thanks. And thanks all.

Ctznkane525 · Accepted Answer · 2018-07-12 15:40:32Z

1

Assuming building_id is numeric, I instead recommend you write:

if (! System.Convert.IsDbNull(dr["building_id"]))

If it's text, I'd recommend this:

if (! System.Convert.IsDbNull(dr["building_id"]) && ! String.IsNullOrWhiteSpace(dr["building_id"].ToString()))

This is how we check for nulls, blanks and whitespace.

answered Jul 12, 2018 at 15:40

Ctznkane525

7,5453 gold badges20 silver badges41 bronze badges

Collectives™ on Stack Overflow

Variable creation inside an OracleDataReader in C#

2 Answers 2

5 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

5 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related