update Visit method in RelationalProjectionBindingExpressionVisitor class

Author: Abde1rahman1

src/EFCore.Relational/Query/Internal/RelationalProjectionBindingExpressionVisitor.cs

@@ -124,7 +124,16 @@ public virtual Expression Translate(SelectExpression selectExpression, Expressio
                         return _selectExpression.GetProjection(projectionBindingExpression) switch
                         {
                             StructuralTypeProjectionExpression projection => AddClientProjection(projection, typeof(ValueBuffer)),
-                            SqlExpression mappedSqlExpression => AddClientProjection(mappedSqlExpression, expression.Type),
+                           SqlExpression mappedSqlExpression => AddClientProjection(
+                                mappedSqlExpression,
+                                (mappedSqlExpression switch
+                                {
+                                    ColumnExpression c => c.IsNullable,
+                                    SqlFunctionExpression f => f.IsNullable,
+                                    _ => mappedSqlExpression.Type.IsNullableType()
+                                })
+                                    ? expression.Type.MakeNullable()
+                                    : expression.Type),
                             _ => throw new InvalidOperationException(CoreStrings.TranslationFailed(projectionBindingExpression.Print()))
                         };
 
@@ -234,8 +243,19 @@ public virtual Expression Translate(SelectExpression selectExpression, Expressio
                 {
                     case SqlExpression sqlExpression:
                         _projectionMapping[_projectionMembers.Peek()] = sqlExpression;
+                        
+                        // فحص ذكي للـ Nullability يغطي العمود والدالة وأي تعبير آخر
+                        var isNullable = sqlExpression switch
+                        {
+                            ColumnExpression c => c.IsNullable,
+                            SqlFunctionExpression f => f.IsNullable,
+                            _ => sqlExpression.Type.IsNullableType()
+                        };
+
                         return new ProjectionBindingExpression(
-                            _selectExpression, _projectionMembers.Peek(), expression.Type);
+                            _selectExpression,
+                            _projectionMembers.Peek(),
+                            isNullable ? expression.Type.MakeNullable() : expression.Type);
 
                     // This handles the case of a complex type being projected out of a Select.
                     // Note that an entity type being projected is (currently) handled differently