Add demo

Src/Asp.NetCore2/SqlSeverTest/UserTestCases/UnitTest/Unitsdfyasfs3lsss.cs

@@ -25,6 +25,33 @@ namespace OrmTest
                     n=SqlFunc.MappingColumn<bool>("1=1")?true:false
                 }).ToList();
 
+            var sql= db.Queryable<UserInfo001>()
+                .Where(it => it.UserId==-1)
+                .LeftJoinIF<UserInfo001>(false,(x, y) => false)
+                .ToSqlString();
+
+            if (!sql.Contains("[UserId] = -1 ")) throw new Exception("unit error");
+
+            var sq2 = db.Queryable<UserInfo001>()
+               .Where(it => it.UserId == -1)
+               .InnerJoinIF<UserInfo001>(false, (x, y) => false)
+               .ToSqlString();
+
+            if (!sq2.Contains("[UserId] = -1 ")) throw new Exception("unit error");
+
+
+            var sql3 = db.Queryable<UserInfo001>() 
+           .LeftJoinIF<UserInfo001>(false, (x, y) => false)
+           .ToSqlString();
+
+            if (!sql3.EndsWith("FROM [Unitadfaysd22] [x] ")) throw new Exception("unit error");
+
+            var sq4 = db.Queryable<UserInfo001>() 
+               .InnerJoinIF<UserInfo001>(false, (x, y) => false)
+               .ToSqlString();
+
+            if (!sq4.EndsWith("FROM [Unitadfaysd22] [x] ")) throw new Exception("unit error");
+
             var userInfo2 = db.Queryable<UserInfo001>()
              .Where(t => x.Any(s =>  t.UserName ==s.UserName && t.Context == s.Context))
              .ToList();

Src/Asp.NetCore2/SqlSugar/Abstract/QueryableProvider/QueryableProvider.cs

@@ -234,7 +234,14 @@ namespace SqlSugar
             if (isJoin == false)
             {
                 result.QueryBuilder.JoinQueryInfos.Remove(result.QueryBuilder.JoinQueryInfos.Last());
-                result.QueryBuilder.AsTables = oldAsName;
+                if (oldAsName?.Any() == false && result.QueryBuilder.AsTables?.Any() == true)
+                {
+                    //no things
+                }
+                else
+                {
+                    result.QueryBuilder.AsTables = oldAsName;
+                }
             }
             return result;
         }