I use SqlDataReader.GetValue method to read values from DB:
Log.WriteLine("Value of CompanyName column:" + thisReader.GetValue(1));
As parameter GetValue get index of column. How could I specify Column Name instead index?
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3 Answers
Log.WriteLine("Value of CompanyName column:" + thisReader["CompanyName"]);
answered Dec 28, 2011 at 12:34
Mauricio Scheffer
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6 Comments
algot
I used as workaround following -
Log.WriteLine("Value of CompanyName column:" + thisReader.GetValue(thisReader.GetOrdinal("CompanyName"))); What [] means?
Mauricio Scheffer
@algot it's an indexed property, see msdn.microsoft.com/en-us/library/aa288464.aspx or msdn.microsoft.com/en-us/library/2549tw02.aspx
tmighty
I don't understand the syntax "thisReader["CompanyName"]). It is in no way logical. Logical would be "thisReader.fields("CompanyName").value". But who am I to judge...
Rob
@tmighty: This is a very common notation for indexed collections, not only in C#. The index will often be an integer, but it can also be of another type, such as string.
Mark Schultheiss
Note to self, internally this does
return GetValue(GetOrdinal(name)); reference referencesource.microsoft.com/#system.data/system/data/… |
You can also do this.
//find the index of the CompanyName column
int columnIndex = thisReader.GetOrdinal("CompanyName");
//Get the value of the column. Will throw if the value is null.
string companyName = thisReader.GetString(columnIndex);
6 Comments
curiousBoy
I was thinking in which case this could have more benefit then directly reading data from reader as thisReader["CompanyName"]. Can you please give any specific case for it? Thanks a lot btw.
David Molyneux
@curiousBoy doing it this way will make it easier to check if the column exists, also makes sure the value you are selecting is in the correct dataformat e.g GetString, GetInt32 it doesnt just return an object you then have to cast. This is why i would use this method
curiousBoy
@DavidMolyneux thx for your comment, as far as I understand from your explanation, it basically do "null check" for the string and throws an error in case of the value is null. This also makes me thing that this is just for the type of string. Other than that, for instance : "int productQuantiy = thisReader["ProductQuantity"] " would throw an error if the ProductQuantity doesn't have a valid int value, wouldn't it? thx again.
David Molyneux
@curiousBoy 'int productQuantiy = thisReader["ProductQuantity"]' wouldnt work the compiler wont let you assign an object to a int you would have to parse/convert the object first.
Guy Schalnat
For performance reasons, Microsoft now recommends you call your GetOrdinal outside your read loop, and only call GetString(int) inside the loop
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thisReader.GetString(int columnIndex)
1 Comment
ekad
Please add some explanation of how this answer actually solves the problem.