Update exp to sql

Src/Asp.NetCore2/SqlSeverTest/SqlSeverTest/UnitTest/UQueryable.cs

@@ -95,9 +95,28 @@ namespace OrmTest
                 a =  it.a.Value
             }).ToSql();
             UValidate.Check(x.Key, "SELECT  [a] AS [a]  FROM [BoolTest2] ", "Queryable");
+
+            Db.CodeFirst.InitTables<UnitDecimal>();
+
+            Db.Queryable<UnitDecimal>().Select(it =>
+
+            new UnitDecimal2
+            {
+                x1 = it.x1 * it.x2
+            }).ToList();
         }
 
 
+
+        public class UnitDecimal
+        {
+            public decimal x1 { get; set; }
+            public decimal x2 { get; set; }
+        }
+        public class UnitDecimal2 {
+          public decimal? x1 { get; set; }
+        }
+
         /// <summary>
         /// 系统用户表实体模型类
         /// </summary>

Src/Asp.NetCore2/SqlSeverTest/SqlSugar/ExpressionsToSql/Common/ExpressionTool.cs

@@ -59,7 +59,22 @@ namespace SqlSugar
             else
                 return value;
         }
-
+        public static Type GetMemberInfoType(MemberInfo member)
+        {
+            switch (member.MemberType)
+            {
+                case MemberTypes.Event:
+                    return ((EventInfo)member).EventHandlerType;
+                case MemberTypes.Field:
+                    return ((FieldInfo)member).FieldType;
+                case MemberTypes.Method:
+                    return ((MethodInfo)member).ReturnType;
+                case MemberTypes.Property:
+                    return ((PropertyInfo)member).PropertyType;
+                default:
+                    return null;
+            }
+        }
         public static bool IsLogicOperator(string operatorValue)
         {
             return operatorValue == "&&" || operatorValue == "||"||operatorValue == "AND" || operatorValue == "OR";

Src/Asp.NetCore2/SqlSeverTest/SqlSugar/ExpressionsToSql/ResolveItems/MemberInitExpressionResolve.cs

@@ -242,10 +242,28 @@ namespace SqlSugar
                 MemberAssignment memberAssignment = (MemberAssignment)binding;
                 var memberName = memberAssignment.Member.Name;
                 var item = memberAssignment.Expression;
+                if (IsNullable(item) && item is UnaryExpression)
+                {
+                    var memtype = ExpressionTool.GetMemberInfoType(memberAssignment.Member);
+                    if (IsNullable(memtype) && UtilMethods.GetUnderType(memtype) == UtilMethods.GetUnderType(item.Type))
+                    {
+                        item = (item as UnaryExpression).Operand;
+                    }
+                }
                 ResolveNewExpressions(parameter, item, memberName);
             }
         }
 
+        private static bool IsNullable(Type memtype)
+        {
+            return memtype.Name == "Nullable`1";
+        }
+
+        private static bool IsNullable(Expression item)
+        {
+            return item.Type.Name == "Nullable`1";
+        }
+
         //private bool IsSubMethod(MethodCallExpression express)
         //{
         //    return SubTools.SubItemsConst.Any(it =>express.Object != null && express.Object.Type.Name == "Subqueryable`1");