Determine if DataColumn is numeric
Is there a better way than this to check if a DataColumn in a DataTable is numeric (coming from a SQL Server database)?
Database db = DatabaseFactory.CreateDatabase();
DbCommand cmd = db.GetStoredProcCommand("Get_Some_Data");
DataSet ds = db.ExecuteDataSet(cmd);
foreach (DataTable tbl in ds.Tables) {
foreach (DataColumn col in tbl.Columns) {
if (col.DataType == typ开发者_高级运维eof(System.Single)
|| col.DataType == typeof(System.Double)
|| col.DataType == typeof(System.Decimal)
|| col.DataType == typeof(System.Byte)
|| col.DataType == typeof(System.Int16)
|| col.DataType == typeof(System.Int32)
|| col.DataType == typeof(System.Int64)) {
// this column is numeric
} else {
// this column is not numeric
}
}
}
There is no good way to check if the type is numeric except comparing it to the actual types.
This is especially true if the definition of numeric is a bit different (in your case, according to code, - unsigned integers are not numerics).
Another thing is that DataColumn.DataType according to MSDN only supports following types:
- Boolean
- Byte
- Char
- DateTime
- Decimal
- Double
- Int16
- Int32
- Int64
- SByte
- Single
- String
- TimeSpan
- UInt16
- UInt32
- UInt64
- Byte[]
The bolded types are numerics (as I define it) so you need to make sure you check them.
I personally would write an extension method for the DataColumn type (not for the TYPE!).
I hate the if...then..else thing so instead I use a SETS-based approach, like this:
public static bool IsNumeric(this DataColumn col) {
if (col == null)
return false;
// Make this const
var numericTypes = new [] { typeof(Byte), typeof(Decimal), typeof(Double),
typeof(Int16), typeof(Int32), typeof(Int64), typeof(SByte),
typeof(Single), typeof(UInt16), typeof(UInt32), typeof(UInt64)};
return numericTypes.Contains(col.DataType);
}
And the usage would be:
if (col.IsNumeric()) ....
which is easy enough for me
Another method without using Arrays, just by one line of code:
return col != null && "Byte,Decimal,Double,Int16,Int32,Int64,SByte,Single,UInt16,UInt32,UInt64,".Contains(col.DataType.Name + ",");
This line of code can be used either as a normal helper method or as an extension method.
Maybe you could make it shorter with:
System.Type theType = col.DataType AS System.Type
if(theType == System.Single || theType == System.Double...) {}
精彩评论