Remove sbyte from clr mappings. Not needed as EF Core will use automatic conversions for those types. EF Core SQL Server behaves the same

src/EFCore.Jet/Storage/Internal/JetDecimalTypeMapping.cs

@@ -24,7 +24,7 @@ namespace EntityFrameworkCore.Jet.Storage.Internal
             DbType? dbType = null,
             int? precision = null,
             int? scale = null,
-            StoreTypePostfix storeTypePostfix = StoreTypePostfix.None)
+            StoreTypePostfix storeTypePostfix = StoreTypePostfix.PrecisionAndScale)
             : base(
                 new RelationalTypeMappingParameters(
                         new CoreTypeMappingParameters(typeof(decimal)),
@@ -70,6 +70,16 @@ namespace EntityFrameworkCore.Jet.Storage.Internal
             {
                 parameter.Size = Size.Value;
             }
+
+            if (Precision.HasValue)
+            {
+                parameter.Precision = unchecked((byte)Precision.Value);
+            }
+
+            if (Scale.HasValue)
+            {
+                parameter.Scale = unchecked((byte)Scale.Value);
+            }
         }
     }
 }

src/EFCore.Jet/Storage/Internal/JetTypeMappingSource.cs

@@ -40,7 +40,7 @@ namespace EntityFrameworkCore.Jet.Storage.Internal
         private readonly JetFloatTypeMapping _single = new JetFloatTypeMapping("single");
         private readonly JetDoubleTypeMapping _double = new JetDoubleTypeMapping("double");
 
-        private readonly JetDecimalTypeMapping _decimal = new JetDecimalTypeMapping("decimal", DbType.Decimal, precision: 18, scale: 10, StoreTypePostfix.PrecisionAndScale);
+        private readonly JetDecimalTypeMapping _decimal = new JetDecimalTypeMapping("decimal", DbType.Decimal, precision: 18, scale: 2, StoreTypePostfix.PrecisionAndScale);
         private readonly JetCurrencyTypeMapping _currency = new JetCurrencyTypeMapping("currency");
 
         private readonly JetDateTimeTypeMapping _datetime;
@@ -181,14 +181,11 @@ namespace EntityFrameworkCore.Jet.Storage.Internal
                     {"timestamp",                  _rowversion},
                 };
 
-            // Note: sbyte, ushort, uint, char, long and ulong type mappings are not supported by Jet.
-            // We would need the type conversions feature to allow this to work - see https://github.com/aspnet/EntityFramework/issues/242.
             _clrTypeMappings
                 = new Dictionary<Type, RelationalTypeMapping>
                 {
                     {typeof(bool), _bool},
                     {typeof(byte), _byte},
-                    {typeof(sbyte), _smallint},
                     {typeof(short), _smallint},
                     {typeof(int), _integer},
                     {typeof(long), _bigint},