Add SqlFunc.MergeString

Src/Asp.Net/MySqlTest/Demos/1_Query.cs

@@ -333,6 +333,7 @@ namespace OrmTest.Demo
             var db = GetInstance();
             var t1 = db.Queryable<Student>().Where(it => SqlFunc.ToLower(it.Name) == SqlFunc.ToLower("JACK")).ToList();
             var t2 = db.Queryable<Student>().Where(it => SqlFunc.IsNull(it.Name, "nullvalue") == "nullvalue").ToList();
+            var t3 = db.Queryable<Student>().Where(it => SqlFunc.MergeString("a", it.Name) == "nullvalue").ToList();
             //SELECT [Id],[SchoolId],[Name],[CreateTime] FROM [Student]  WHERE ((LOWER([Name])) = (LOWER(@MethodConst0)) )
 
             /***More Functions***/

Src/Asp.Net/SqlServerTest/Demos/1_Query.cs

@@ -434,6 +434,7 @@ namespace OrmTest.Demo
             var db = GetInstance();
             var t1 = db.Queryable<Student>().Where(it => SqlFunc.ToLower(it.Name) == SqlFunc.ToLower("JACK")).ToList();
             var t2 = db.Queryable<Student>().Where(it => SqlFunc.IsNull(it.Name,"nullvalue")=="nullvalue").ToList();
+            var t3 = db.Queryable<Student>().Where(it => SqlFunc.MergeString("a",it.Name) == "nullvalue").ToList();
             //SELECT [Id],[SchoolId],[Name],[CreateTime] FROM [Student]  WHERE ((LOWER([Name])) = (LOWER(@MethodConst0)) )
 
             /***More Functions***/

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

@@ -302,7 +302,7 @@ namespace SqlSugar
 
         public virtual string MergeString(params string[] strings)
         {
-            return string.Join("", strings);
+            return string.Join("+", strings);
         }
 
         public virtual string Pack(string sql)

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

@@ -68,6 +68,12 @@ namespace SqlSugar
         public static bool Between(object value, object start, object end) { throw new NotSupportedException("Can only be used in expressions"); }
         public static TResult IIF<TResult>(bool Expression, TResult thenValue, TResult elseValue) { throw new NotSupportedException("Can only be used in expressions"); }
         public static TResult IsNull<TResult>(TResult thisValue, TResult ifNullValue) { throw new NotSupportedException("Can only be used in expressions"); }
+        public static string MergeString(string value1,string value2) { throw new NotSupportedException("Can only be used in expressions"); }
+        public static string MergeString(string value1, string value2,string value3) { throw new NotSupportedException("Can only be used in expressions"); }
+        public static string MergeString(string value1, string value2,string value3,string value4) { throw new NotSupportedException("Can only be used in expressions"); }
+        public static string MergeString(string value1, string value2, string value3, string value4,string value5) { throw new NotSupportedException("Can only be used in expressions"); }
+        public static string MergeString(string value1, string value2, string value3, string value4, string value5,string value6) { throw new NotSupportedException("Can only be used in expressions"); }
+        public static string MergeString(string value1, string value2, string value3, string value4, string value5, string value6,string value7) { throw new NotSupportedException("Can only be used in expressions"); }
         public static int ToInt32(object value) { return value.ObjToInt(); }
         public static long ToInt64(object value) { return Convert.ToInt64(value); }
         /// <summary>

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

@@ -204,9 +204,9 @@ namespace SqlSugar
                 };
                 AppendMember(parameter, isLeft, GetToDate(this.Context.DbMehtods.MergeString(
                     this.GetDateValue(parameter.CommonTempData, DateType.Year),
-                    "+'-'+",
+                    "'-'",
                     this.GetDateValue(parameter.CommonTempData, DateType.Month),
-                    "+'-'+",
+                    "'-'",
                     this.GetDateValue(parameter.CommonTempData, DateType.Day))));
             }
             parameter.CommonTempData = oldCommonTempDate;

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

@@ -409,6 +409,8 @@ namespace SqlSugar
                     return mappingColumnResult;
                 case "IsNull":
                     return this.Context.DbMehtods.IsNull(model);
+                case "MergeString":
+                        return this.Context.DbMehtods.MergeString(model.Args.Select(it=>it.MemberName.ObjToString()).ToArray());
                 case "GetSelfAndAutoFill":
                     this.Context.Parameters.RemoveAll(it => it.ParameterName == model.Args[0].MemberName.ObjToString());
                     return this.Context.DbMehtods.GetSelfAndAutoFill(model.Args[0].MemberValue.ObjToString(), this.Context.IsSingle);

Src/Asp.Net/SqlSugar/Realization/Oracle/SqlBuilder/OracleExpressionContext.cs

@@ -164,5 +164,9 @@ namespace SqlSugar
             return string.Format("NVL({0},{1})", parameter.MemberName, parameter1.MemberName);
         }
 
+        public override string MergeString(params string[] strings)
+        {
+            return string.Join("||", strings).Replace("+", "");
+        }
     }
 }