Get datatype from values passed as string

Question

I am writing a framework that will connect to many different data source types and return values from these sources. The easy ones are SQL, Access and Oracle. The tougher ones a

Answer 1

I've come up with the following solution which works:

enum dataType
    {
        System_Boolean = 0,
        System_Int32 = 1,
        System_Int64 = 2,
        System_Double = 3,
        System_DateTime = 4,
        System_String = 5
    }

    private dataType ParseString(string str)
    {

        bool boolValue;
        Int32 intValue;
        Int64 bigintValue;
        double doubleValue;
        DateTime dateValue;

        // Place checks higher in if-else statement to give higher priority to type.

        if (bool.TryParse(str, out boolValue))
            return dataType.System_Boolean;
        else if (Int32.TryParse(str, out intValue))
            return dataType.System_Int32;
        else if (Int64.TryParse(str, out bigintValue))
            return dataType.System_Int64;
        else if (double.TryParse(str, out doubleValue))
            return dataType.System_Double;
        else if (DateTime.TryParse(str, out dateValue))
            return dataType.System_DateTime;
        else return dataType.System_String;

    }


    /// 

    /// Gets the datatype for the Datacolumn column
    /// 
    /// Datacolumn to get datatype of
    /// DataTable to get datatype from
    /// ref value to return size for string type
    /// 
    public Type GetColumnType(DataColumn column, DataTable dt, ref int colSize)
    {

        Type T;
        DataView dv = new DataView(dt);
        //get smallest and largest values
        string colName = column.ColumnName;

        dv.RowFilter = "[" + colName + "] = MIN([" + colName + "])";
        DataTable dtRange = dv.ToTable();
        string strMinValue = dtRange.Rows[0][column.ColumnName].ToString();
        int minValueLevel = (int)ParseString(strMinValue);

        dv.RowFilter = "[" + colName + "] = MAX([" + colName + "])";
        dtRange = dv.ToTable();
        string strMaxValue = dtRange.Rows[0][column.ColumnName].ToString();
        int maxValueLevel = (int)ParseString(strMaxValue);
        colSize = strMaxValue.Length;

        //get max typelevel of first n to 50 rows
        int sampleSize = Math.Max(dt.Rows.Count, 50);
        int maxLevel = Math.Max(minValueLevel, maxValueLevel);

        for (int i = 0; i < sampleSize; i++)
        {
            maxLevel = Math.Max((int)ParseString(dt.Rows[i][column].ToString()), maxLevel);
        }

        string enumCheck = ((dataType)maxLevel).ToString();
        T = Type.GetType(enumCheck.Replace('_', '.'));

        //if typelevel = int32 check for bit only data & cast to bool
        if (maxLevel == 1 && Convert.ToInt32(strMinValue) == 0 && Convert.ToInt32(strMaxValue) == 1)
        {
            T = Type.GetType("System.Boolean");
        }

        if (maxLevel != 5) colSize = -1;


        return T;
    }