We have created a synonym in DB but when we trying to execute the synonym then it gives error ORA-00980: synonym translation is no longer valid. we have another clone environment, there the same synonym is working fine. Can any one please help me on that.
Various reasons are possible. For example:
synonym is based on a table/view/other synonym which has been dropped, and that invalidated the synonym you're selecting from
if some of these objects (you used to create the synonym) belong to other user(s), they might have revoked privileges you previously had
you created a synonym based on object that doesn't exist; for example, you misspelled table's name (e.g. DPET instead of DEPT)
What to do? Check options I mentioned and recreate the synonym.
Related
I am trying to figure out (at this point I think the answer is No) if it is possible to build a index on a List Attribute and query NOT_CONTAINS on that attribute.
Example table:
Tasks
Task_id: string
solved_by: List<String> # stores list of user_ids who previously solved this task.
My query would be:
Get me all the tasks not yet solved by current_user
select * from tasks where tasks.solved_by NOT_CONTAINS current_user_id
Is it possible to do this without full scans. I tried creating an attribute of type L but aws cli errors out saying Member must satisfy enum value set: [B, N, S]
If this is not possible with dynamodb, please suggest what datastore I can use.
Any help is highly appreciated. Thanks!
As you found out, and as the error you got suggests, this is NOT possible.
However, I'd argue if your design couldn't be improved. Storing a potentially unbound list of entries (users in your case) inside a single item, which is limited to 400kb seems dangerous.
If instead, you'd store for each task the information that a particular user resolved it as a separate item (partition key - task_id, sort key - user_id) than you could easily look up if a user solved a task or not. You could also store additional information about the particular solution or attempts.
If you haven't heard of DynamoDB single table design yet, or how to overload indexes, I can recommend looking at
https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/bp-modeling-nosql-B.html
https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/bp-gsi-overloading.html
https://www.dynamodbbook.com/
Update
I just realised, you care about a negation (NOT_CONTAINS) - for those, you can't use an index anyway. For the sort key you can only use positive comparison (=, <, >, <=, >=, between, begins_with): https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Query.html#Query.KeyConditionExpressions
So you might have to rethink the whole approach, to better pre-process the data stored in DDB, so it's easier to fetch, or pick a different database.
In your original question, you defined your access pattern as
Get me all the tasks not yet solved by current_user
In a later comment, you clarified that the access pattern is
A solver should be shown a task that is not yet solved by them.
which is a slightly different access pattern.
Here's one way you could fetch a task not yet solved by a user.
In this data model, I chose to model Users and Tasks as separate items. Tasks have numerically increasing ID's. Each User item should start with the lastSolved attribute set to 1. Each time you fetch a new Task for a user, you fetch TASK#{last_solved+1} and increment the lastSolved attribute by 1.
You could probably take a similar approach by using timestamps instead of numbers... anything sortable, really.
When I scaffold my database get the following error:
Referenced table `contentcategory` is not in dictionary.
Referenced table `contentcategory` is not in dictionary.
Referenced table `contenttype` is not in dictionary.
Referenced table `content` is not in dictionary.
I Use Mysql and Pomelo.EntityFrameworkCore.MySql
This is very likely to be a casing issue, where MySQL assumes the table name to be contentcategory for the reference, while it is actually something like ContentCategory.
We have a pull request for this open since April, that looks abandoned by the original contributor.
I will fix the PR and merge it, so that the workaround for this issue will be part of our nightly builds as of tomorrow.
The linked PR also contains the information of how this issue can arise:
Okay, that is in line with what I experienced as well. So manually (either by writing the name in the GUI or by using an ALTER TABLE statement directly) adding a reference with different casing (on a server with case insensitive file name handling) or disabling SQL Identifiers are Case Sensitive [in MySQL Workbench] can lead to this result.
Technically, this is a MySQL or Workbench bug, but we will implement a workaround for it anyway.
Using Oracle 11gR2
You can't create a username starting with a number:
SQL> create user 123 identified by temp;
create user 123 identified by temp
*
ERROR at line 1:
ORA-01935: missing user or role name
However, you can create it as:
SQL> create user "123" identified by temp;
User created.
Somebody knows possible problems with this kind of users?
Somebody knows oracle rules/reasons why you can't create it without quotes, ie, to have usernames starting with numbers?
Thanks in advance
Problems with quoted identifiers
Quoted identifiers can be successfully used for almost any Oracle object, including users. In theory, they work everywhere. In practice, you will run into many inconveniences and problems with quoted identifiers.
From the SQL Language Reference:
"Note: Oracle does not recommend using quoted identifiers for database object names. These quoted identifiers are accepted by SQL*Plus, but they may not be valid when using other tools that manage database objects."
Once you use double quotes, every reference to that object must use double quotes, and the correct case. You'll find lots of problems with tools that don't always use double quotes. And problems with scripts that look at metadata and don't always add double quotes. Quoted identifiers are just asking for trouble.
Why does Oracle have quoted identifiers?
This question is harder to answer, but I would guess limiting the types of characters used by objects makes parsing much easier. SQL already has a lot of keywords, and has many weird language ambiguities. If object names started with numbers it would make it difficult to differentiate between real numbers and objects.
For example, without quoted identifiers, this simple statement could be a mess:
select 1.1 + 2.2 from some_table;
Without restricting object names, 1.1 could be a huge number of things, and the parser would have to look for objects named "1", and then dependent objects named "1", and then determine if that takes precedence over the number "1.1".
Weird names are possible in languages, but I assume when someone wrote the first SQL compiler 40 years ago they decided not to make their lives so complicated just to accommodate a few weird names.
Check if the user name is not present in reserved words and doesn't start with number:
SELECT *
FROM v$reserved_words
ORDER BY keyword
If you are creating user try this:
alter session set "_ORACLE_SCRIPT"=true;
CREATE USER oe IDENTIFIED BY oe;
check your connection type is cdb or not. if it is cdb as shown in the below
image
use prefix c## before the username in the command for creating user
I'm having a hard time debugging a particular problem and have a couple questions. First, here is what's going on:
I have a relatively simple table called Employees, which has a primary key / identity Id. There is also a Username column - which is a GUID foreign key to my aspnet_Users table used for membership. Finally, there is another foreign key Team_Id which points to another table, Teams.
All I'm really trying to do is give a selected employee's Id and pass it to a method in the DAL which then finds the employee with the following statement:
var employee = entities.Employees.Where(emp => emp.Id == employeeId);
Once the employee is retrieved, I want to use another value which is passed to the same method - the selected team's Id - to update the employee's Team_Id value (which team they are assigned to), using the following:
employee.First().Team_Id = teamId;
entities.SaveChanges();
I get the exception
Invalid column name: {Name}
which doesn't make sense to me, because Employee doesn't have a name column.
All of that said, my questions are:
Where could the mix up possibly be coming from? I've tried thinking up a way to step through the code, but it seems like the error is somewhere in the query itself so I'm not really sure how to trace the execution of the query itself.
Is it possible that it may have something to do with my generated Entities? I noticed that when I type employee.First(). Name comes up in Intellisense. I'm really confused by that, since as I've mentioned there is no Name column in the employees table.
Fixed the issue. I just removed the existing Entity Framework Model and re-added it.
As far as the query goes, you can always use SQL Profiler to watch what scripts are actually running. That's a good way to troubleshoot generated SQL anyway.
For your property, somehow that did make it to your class, so your data model thinks it's there, for whatever reason. I'd say just go to your data model (you don't mention if this this is EF or LINQ-to-SQL), and you'll see "Name" there. Just remove it, and it will remove it from the class, and from the data access stuff.
I is there a way to add "additional info" to a sqlite database. Something like date of creation of a database, amount of entries or name of user who created it. If I don't want to create special tables in order to store all this info especially if there will only be one of each type.
Thank you in advance.
Why not use one special table and store each special value as a name-value pair?
CREATE TABLE SpecialInfoKeyValues (
Key VARCHAR UNIQUE COLLATE NOCASE,
Value
);
Since SQLite uses "manifest typing," you can store any kind of value you want in there.
In short, no. SQLite has no concept of users, and doesn't store creation metadata.
No, there is no way to do that, you will have to use a "special" table to carry data within the file, or you will have to use external means.
There are, however, two version counters stored within the database itself: the schema_version and the user_version (see Pragmas to query/modify version values for details.) Perhaps you could abuse those. Please keep in mind, though, that by default the sqlite3 shell application does not store those when you use the .dump command to dump the database into a textual representation.