Fix schema table column ordering.

Author: Giorgi

DuckDB.NET.Data/DuckDBDataReader.cs

@@ -290,35 +290,34 @@ public override DataTable GetSchemaTable()
         {
             Columns =
             {
-                { "ColumnOrdinal", typeof(int) },
-                { "ColumnName", typeof(string) },
-                { "DataType", typeof(Type) },
-                { "ColumnSize", typeof(int) },
-                { "AllowDBNull", typeof(bool) },
-                { "NumericScale", typeof(byte) },
-                { "NumericPrecision", typeof(byte) }
+                { SchemaTableColumn.ColumnName, typeof(string) },
+                { SchemaTableColumn.ColumnOrdinal, typeof(int) },
+                { SchemaTableColumn.ColumnSize, typeof(int) },
+                { SchemaTableColumn.NumericPrecision, typeof(byte)},
+                { SchemaTableColumn.NumericScale, typeof(byte) },
+                { SchemaTableColumn.DataType, typeof(Type) },
+                { SchemaTableColumn.AllowDBNull, typeof(bool)  }
             }
         };
 
         var rowData = new object[7];
 
         for (var i = 0; i < FieldCount; i++)
         {
-            rowData[0] = i;
-            rowData[1] = GetName(i);
-            rowData[2] = GetFieldType(i);
-            rowData[3] = -1;
-            rowData[4] = true;
+            rowData[0] = GetName(i);
+            rowData[1] = i;
+            rowData[2] = -1;
+            rowData[5] = GetFieldType(i);
+            rowData[6] = true;
 
-            if (vectorReaders[i] is DecimalVectorDataReader decimalVectorDataReader) 
+            if (vectorReaders[i] is DecimalVectorDataReader decimalVectorDataReader)
             {
-                rowData[5] = decimalVectorDataReader.Scale;
-                rowData[6] = decimalVectorDataReader.Precision;
-            } 
-            else 
+                rowData[4] = decimalVectorDataReader.Scale;
+                rowData[3] = decimalVectorDataReader.Precision;
+            }
+            else
             {
-                rowData[5] = DBNull.Value;
-                rowData[6] = DBNull.Value;
+                rowData[3] = rowData[4] = DBNull.Value;
             }
 
             table.Rows.Add(rowData);

DuckDB.NET.Data/Internal/Reader/DecimalVectorDataReader.cs

@@ -6,27 +6,19 @@ namespace DuckDB.NET.Data.Internal.Reader;
 
 internal sealed class DecimalVectorDataReader : NumericVectorDataReader
 {
-    private readonly byte scale;
-    private readonly byte precision;
     private readonly DuckDBType decimalType;
 
     internal unsafe DecimalVectorDataReader(IntPtr vector, void* dataPointer, ulong* validityMaskPointer, DuckDBType columnType, string columnName) : base(dataPointer, validityMaskPointer, columnType, columnName)
     {
         using var logicalType = NativeMethods.Vectors.DuckDBVectorGetColumnType(vector);
-        scale = NativeMethods.LogicalType.DuckDBDecimalScale(logicalType);
-        precision = NativeMethods.LogicalType.DuckDBDecimalWidth(logicalType);
+        Scale = NativeMethods.LogicalType.DuckDBDecimalScale(logicalType);
+        Precision = NativeMethods.LogicalType.DuckDBDecimalWidth(logicalType);
         decimalType = NativeMethods.LogicalType.DuckDBDecimalInternalType(logicalType);
     }
 
-    internal byte Scale 
-    {
-        get => scale;
-    }
+    internal byte Scale { get; }
 
-    internal byte Precision
-    {
-        get => precision;
-    }
+    internal byte Precision { get; }
 
     protected override T GetValidValue<T>(ulong offset, Type targetType)
     {
@@ -51,7 +43,7 @@ internal override object GetValue(ulong offset, Type targetType)
 
     private decimal GetDecimal(ulong offset)
     {
-        var pow = (decimal)Math.Pow(10, scale);
+        var pow = (decimal)Math.Pow(10, Scale);
         switch (decimalType)
         {
             case DuckDBType.SmallInt: