See This StackOverflow thread
The GetSchema() function will not return the info that you want. Nor will examining the DataTable schema properties. You'll have to go to a lower level and that will depend on the DBMS and likely its version.
The member below retrieves all tables with identity columns and then looks to match a specific table passed as an argument. The code can be modified to either return all the tables or the query optimized to look only for the table of interest.
// see: https://stackoverflow.com/questions/87747/how-do-you-determine-what-sql-tables-have-an-identity-column-programatically
private static string GetIdentityColumnName(SqlConnection sqlConnection, Tuple<string, string> table)
{
string columnName = string.Empty;
const string commandString =
"select TABLE_SCHEMA, TABLE_NAME, COLUMN_NAME from INFORMATION_SCHEMA.COLUMNS "
+ "where TABLE_SCHEMA = 'dbo' and COLUMNPROPERTY(object_id(TABLE_NAME), COLUMN_NAME, 'IsIdentity') = 1 "
+ "order by TABLE_NAME";
DataSet dataSet = new DataSet();
SqlDataAdapter sqlDataAdapter = new SqlDataAdapter();
sqlDataAdapter.SelectCommand = new SqlCommand(commandString, sqlConnection);
sqlDataAdapter.Fill(dataSet);
if (dataSet.Tables.Count > 0 && dataSet.Tables[0].Rows.Count > 0)
{
foreach (DataRow row in dataSet.Tables[0].Rows)
{
// compare name first
if (string.Compare(table.Item2, row[1] as string, true) == 0)
{
// if the schema as specified, we need to match it, too
if (string.IsNullOrWhiteSpace(table.Item1) || string.Compare(table.Item1, row[0] as string) == 0)
{
columnName = row[2] as string;
break;
}
}
}
}
return columnName;
}
