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Asked: 2026-05-10T22:56:10+00:00

Using the code below, I am returning an nvarchar field from MS SQL 2005

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Using the code below, I am returning an nvarchar field from MS SQL 2005 and keep getting a System.InvalidCastException.

vo.PlacementID = dr.IsDBNull(0) ? null : dr.GetString(0);

The vo.PlacementID variable is of type String so there shouldn’t be a problem. The values I am trying to return are like this (number, number, letter): 00F, 02A, 01F, etc 

System.InvalidCastException: Unable to cast object of type 'System.Int32' to  type 'System.String'.     at System.Data.SqlClient.SqlBuffer.get_String()     at System.Data.SqlClient.SqlDataReader.GetString(Int32 i)

Any help much appreciated.

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1 Answer

  1. If you read the exception again it gives you a clue as to the problem:

    System.InvalidCastException: Unable to cast object of type ‘System.Int32’ to type ‘System.String’. at System.Data.SqlClient.SqlBuffer.get_String() at System.Data.SqlClient.SqlDataReader.GetString(Int32 i)

    Basically the underlying data type being returned in column 0 of your SqlDataReader isn’t a string compatible type, hence the cast exception.

    I’d suggest setting a breakpoint on the offending line and then execute the following line in the immediate window:

    ? dr.GetValue(0).GetType()

    This will tell what type being returned.

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