Bind decimals without table

Author: Giorgi

DuckDB.NET.Bindings/DuckDBDecimal.cs

@@ -3,10 +3,10 @@
 namespace DuckDB.NET.Native;
 
 [StructLayout(LayoutKind.Sequential)]
-public readonly struct DuckDBDecimal
+public readonly struct DuckDBDecimal(byte width, byte scale, DuckDBHugeInt value)
 {
-    public byte Width { get; }
-    public byte Scale { get; }
+    public byte Width { get; } = width;
+    public byte Scale { get; } = scale;
 
-    public DuckDBHugeInt Value { get; }
+    public DuckDBHugeInt Value { get; } = value;
 }

DuckDB.NET.Bindings/NativeMethods/NativeMethods.Value.cs

@@ -47,6 +47,9 @@ public static class Value
         [DllImport(DuckDbLibrary, CallingConvention = CallingConvention.Cdecl, EntryPoint = "duckdb_create_uhugeint")]
         public static extern DuckDBValue DuckDBCreateUHugeInt(DuckDBUHugeInt value);
 
+        [DllImport(DuckDbLibrary, CallingConvention = CallingConvention.Cdecl, EntryPoint = "duckdb_create_decimal")]
+        public static extern DuckDBValue DuckDBCreateDecimal(DuckDBDecimal value);
+
         [DllImport(DuckDbLibrary, CallingConvention = CallingConvention.Cdecl, EntryPoint = "duckdb_create_float")]
         public static extern DuckDBValue DuckDBCreateFloat(float value);
 

DuckDB.NET.Data/DataChunk/Writer/DecimalVectorDataWriter.cs

@@ -16,13 +16,13 @@ internal override bool AppendDecimal(decimal value, ulong rowIndex)
         switch (decimalType)
         {
             case DuckDBType.SmallInt:
-                AppendValueInternal<short>((short)decimal.Multiply(value, new decimal(power)), rowIndex);
+                AppendValueInternal((short)decimal.Multiply(value, new decimal(power)), rowIndex);
                 break;
             case DuckDBType.Integer:
-                AppendValueInternal<int>((int)decimal.Multiply(value, new decimal(power)), rowIndex);
+                AppendValueInternal((int)decimal.Multiply(value, new decimal(power)), rowIndex);
                 break;
             case DuckDBType.BigInt:
-                AppendValueInternal<long>((long)decimal.Multiply(value, new decimal(power)), rowIndex);
+                AppendValueInternal((long)decimal.Multiply(value, new decimal(power)), rowIndex);
                 break;
             case DuckDBType.HugeInt:
                 var integralPart = decimal.Truncate(value);

DuckDB.NET.Data/PreparedStatement/ClrToDuckDBConverter.cs

@@ -159,5 +159,22 @@ private static DuckDBValue StringToDuckDBValue(string? value)
         return NativeMethods.Value.DuckDBCreateVarchar(handle);
     }
 
-    private static DuckDBValue DecimalToDuckDBValue(decimal value) => StringToDuckDBValue(value.ToString(CultureInfo.InvariantCulture));
+    private static DuckDBValue DecimalToDuckDBValue(decimal value)
+    {
+        var bits = decimal.GetBits(value);
+        var scale = (byte)((bits[3] >> 16) & 0x7F);
+        
+        var power = Math.Pow(10, scale);
+
+        var integralPart = decimal.Truncate(value);
+        var fractionalPart = value - integralPart;
+
+        var result = BigInteger.Multiply(new BigInteger(integralPart), new BigInteger(power));
+
+        result += new BigInteger(decimal.Multiply(fractionalPart, (decimal)power));
+
+        int width = result.IsZero ? 1 : (int)Math.Floor(BigInteger.Log10(BigInteger.Abs(result))) + 1;
+
+        return NativeMethods.Value.DuckDBCreateDecimal(new DuckDBDecimal((byte)width, scale, new DuckDBHugeInt(result)));
+    }
 }

DuckDB.NET.Test/Parameters/DecimalParameterTest.cs

@@ -31,7 +31,7 @@ public void SimpleTest()
         }
 
 
-        values = new[] { decimal.One / 3, decimal.MinusOne / 3 };
+        values = [decimal.One / 3, decimal.MinusOne / 3];
 
         foreach (var value in values)
         {
@@ -51,33 +51,28 @@ public void SimpleTest()
     [Fact]
     public void InsertSelectValueTest()
     {
-        DecimalTests(new[]
-        {
+        DecimalTests([
             0m, decimal.Zero,
             decimal.One,
             decimal.One / 2, decimal.MinusOne,
             decimal.MinusOne / 2
-        }, 38, 15);
+        ], 38, 15);
 
-        DecimalTests(new[]
-        {
+        DecimalTests([
             decimal.MinValue, decimal.MaxValue
-        }, 38, 0);
+        ], 38, 0);
 
-        DecimalTests(new[]
-        {
-            decimal.One/3, decimal.MinusOne/3
-        }, 38, 28);
+        DecimalTests([
+            decimal.One/3, decimal.MinusOne/3, -123456789.987654321m
+        ], 38, 28);
 
-        DecimalTests(new[]
-        {
+        DecimalTests([
             0.3333M, 56.1234M
-        }, 8, 4);
+        ], 8, 4);
 
-        DecimalTests(new[]
-        {
+        DecimalTests([
             0.33M, 12.34M
-        }, 4, 2);
+        ], 4, 2);
 
         void DecimalTests(decimal[] values, int precision, int scale)
         {
@@ -118,7 +113,7 @@ public void InsertSelectValueTestWithCulture()
     {
         var defaultCulture = System.Threading.Thread.CurrentThread.CurrentCulture;
 
-        DecimalTests(new[] { "fr-fr", "en-us" }, decimal.One / 2, 38, 15);
+        DecimalTests(["fr-fr", "en-us"], decimal.One / 2, 38, 15);
 
         void DecimalTests(string[] cultures, decimal value, int precision, int scale)
         {
@@ -155,4 +150,22 @@ void DecimalTests(string[] cultures, decimal value, int precision, int scale)
             System.Threading.Thread.CurrentThread.CurrentCulture = defaultCulture;
         }
     }
+
+    [Fact]
+    public void BindParameterWithoutTable()
+    {
+        decimal[] values = [decimal.Zero, 0.00m, 123456789.987654321m, -123456789.987654321m, 1.230m, -1.23m,
+                            0.000000001m, -0.000000001m, 1000000.000000001m, -1000000.000000001m, 1.123456789012345678901m];
+
+        foreach (var value in values)
+        {
+            Command.CommandText = "SELECT ?;";
+            Command.Parameters.Clear();
+            Command.Parameters.Add(new DuckDBParameter(value));
+
+            var result = Command.ExecuteScalar();
+
+            result.Should().BeOfType<decimal>().Subject.Should().Be(value);
+        }
+    }
 }