Add Sqlfunc.Stuff

Src/Asp.Net/SqlSugar/ExpressionsToSql/DbMethods/DefaultDbMethod.cs

@@ -544,5 +544,13 @@ namespace SqlSugar
         {
             return model.Args[0].MemberName + " DESC ";
         }
+        public virtual string Stuff(MethodCallExpressionModel model) 
+        {
+            var parameter1 = model.Args[0];
+            var parameter2 = model.Args[1];
+            var parameter3 = model.Args[2];
+            var parameter4 = model.Args[3];
+            return $" STUFF ({parameter1.MemberName}, {parameter2.MemberName}, {parameter3.MemberName},  {parameter4.MemberName}) ";
+        }
     }
 }

Src/Asp.Net/SqlSugar/ExpressionsToSql/DbMethods/IDbMethods.cs

@@ -85,5 +85,6 @@ namespace SqlSugar
         string LessThanOrEqual(MethodCallExpressionModel model);
         string Asc(MethodCallExpressionModel model);
         string Desc(MethodCallExpressionModel model);
+        string Stuff(MethodCallExpressionModel model);
     }
 }

Src/Asp.Net/SqlSugar/ExpressionsToSql/DbMethods/SqlFunc.cs

@@ -25,6 +25,12 @@ namespace SqlSugar
         {
             throw new NotSupportedException("Can only be used in expressions");
         }
+
+        public static string Stuff(string sourceString, int start, int length, string AddString)
+        {
+            throw new NotSupportedException("Can only be used in expressions");
+        }
+
         public static bool GreaterThanOrEqual(object thisValue, object gtValue)
         {
             throw new NotSupportedException("Can only be used in expressions");

Src/Asp.Net/SqlSugar/ExpressionsToSql/ResolveItems/MethodCallExpressionResolve.cs

@@ -998,6 +998,8 @@ namespace SqlSugar
                         return this.Context.DbMehtods.Asc(model);
                     case "Desc":
                         return this.Context.DbMehtods.Desc(model);
+                    case "Stuff":
+                        return this.Context.DbMehtods.Stuff(model);
                     default:
                         break;
                 }