I have a Dataset that has 3 TablesAdapters linked together (both the relationships and foreign-keys came over from the DB design). I'm trying now to to bind the TableAdapter with the foreign keys on it, I get the following:
"Failed to enable constraints. One or more rows contain values
violating non-null, unique, or foreign-key constraints."
so after a little digging, I found that it doesn't like that I have Identical foreign keys on the TableAdapter (even though the DB contraints are OK with this).
How to I get my DataSet (or the TableAdpapter) to only look at the primary key of the table as a contraint?
Ok, so 5 seconds after I post this I find the answer (isn't that how it always works?)
The problem was that I added a table adapter that queried from my multiple tables, not just a single table. This tableAdapter looks like it just "decided" what columns to use for unique Contraints.
To fix the issue, I had to go into the Dataset designer and search for "UniqueConstraint" until I found the one that was using two foreign key columns of the restraint instead of the one primary key.
Related
I am currently working on a database structure in SQLite Studio (not sure whether that's in itself important, but might as well mention), and error messages are making me wonder whether I'm just going at it the wrong way or there's some subtlety I'm missing.
Assume two tables, people-basics (person-ID, person-NAME, person-GENDER) and people-stats (person-ID, person-NAME, person-SIZE). What I'm looking into achieving is "Every record in people-basics corresponds to a single record in people-stats.", ideally with the added property that person-ID and person-NAME in people-stats reflect the associated person-ID and person-NAME in people-basics.
I've been assuming up to now that one would achieve this with Foreign Keys, but I've also been unable to get this to work.
When I add a person in people-basics, it works fine, but then when I go over to people-stats no corresponding record exists and if I try to create one and fill the Foreign Key column with corresponding data, I get this message: "Cannot edit this cell. Details: Error while executing SQL query on database 'People': no such column: people-basics.person" (I think the message is truncated).
The DDL I currently have for my tables (auto-generated by SQLite Studio based on my GUI operations):
CREATE TABLE [people-basics] (
[person-ID] INTEGER PRIMARY KEY AUTOINCREMENT
UNIQUE
NOT NULL,
[person-NAME] TEXT UNIQUE
NOT NULL,
[person-GENDER] TEXT
);
CREATE TABLE [people-stats] (
[person-NAME] TEXT REFERENCES [people-basics] ([person-NAME]),
[person-SIZE] NUMERIC
);
(I've removed the person-ID column from people-stats for now as it seemed like I should only have one foreign key at a time, not sure whether that's true.)
Alright, that was a little silly.
The entire problem was solved by removing hyphens from table names and column names. (So: charBasics instead of char-basics, etc.)
Ah well.
I'm using Sails.js to build an API for an existing database. Unfortunately, modifying the structure of the database is not an option.
Many tables in the database have status columns of one type or another. They tend to have single-letter values that don't make sense without context. Context is provided by a "lookup" table in the database with 3 primary keys: table_name, column_name, and column_contents. Therefore, if I have a letter returned as a status, I can do a query against the lookup table and check a fourth column, description.
I'd love to configure my Sails.js models to understand all this, but it seems that one-to-many relationships can only be set up for tables with a single primary key. Is that correct?
Based on the "many-to-many" workaround, I assume the sails way to solve this would be to create new tables that are subsets of the "lookup" table (each for a single instance of table_name, column_name). Is there a better way?
I want to make unique constraint in cassandra .
As i want to all the value in my column be unique in my column family
ex:
name-rahul
phone-123
address-abc
now i want that i this row no values equal to rahul ,123 and abc get inserted again on seraching on datastax i found that i can achieve it by doing query on partition key as IF NOT EXIST ,but not getting the solution for getting all the 3 values uniques
means if
name- jacob
phone-123
address-qwe
this should also be not inserted into my database as my phone column has the same value as i have shown with name-rahul.
The short answer is that constraints of any type are not supported in Cassandra. They are simply too expensive as they must involve multiple nodes, thus defeating the purpose of having eventual consistency in first place. If you needed to make a single column unique, then there could be a solution, but not for more unique columns. For the same reason - there is no isolation, no consistency (C and I from the ACID). If you really need to use Cassandra with this type of enforcement, then you will need to create some kind of synchronization application layer which will intercept all requests to the database and make sure that the values are unique, and all constraints are enforced. But this won't have anything to do with Cassandra.
I know this is an old question and the existing answer is correct (you can't do constraints in C*), but you can solve the problem using batched creates. Create one or more additional tables, each with the constrained column as the primary key and then batch the creates, which is an atomic operation. If any of those column values already exist the entire batch will fail. For example if the table is named Foo, also create Foo_by_Name (primary key Name), Foo_by_Phone (primary key Phone), and Foo_by_Address (primary key Address) tables. Then when you want to add a row, create a batch with all 4 tables. You can either duplicate all of the columns in each table (handy if you want to fetch by Name, Phone, or Address), or you can have a single column of just the Name, Phone, or Address.
I have a table that needs to merge from same table in another database.
Condition is one of the column in composite primary key is generated by sequence and may differ in another database.
How can we sync remaining columns in this situation?
Ex.
DB1:
Table: SRE_SERVICE_OPTION
Columns:(OPTION_SET_ID, OPTION_NAME, OPTION_VALUE, VALUE_ORDER)
DB2:
Table: SRE_SERVICE_OPTION
Columns:(OPTION_SET_ID, OPTION_NAME, OPTION_VALUE, VALUE_ORDER)
Primary key:
OPTION_SET_ID, OPTION_NAME, VALUE_ORDER
How should I write merge statement?
You've made the classic error in a distributed database. Simply put, by using two separate sequences you have an inconsistent primary key across the tables. You will only be able to use MERGE if your tables are both separately unique on OPTION_NAME, OPTION_VALUE and VALUE_ORDER.
Your only other hope is that your tables do not contain any duplicated information between them. If so you can simply insert from one into the other.
Otherwise, you are, I'm afraid out of luck. I would re-design your database so that it's impossible to send duplicated information into two different tables with separate, inconsistent, surrogate keys.
I am using Visual Web Developer and Microsoft SQL server. I have a tag table "Entry_Tag" which is as follows:
entry_id
tag_id
I want to make the entry_id and tag_id pairing unique. A particular tag can only be applied to an entry once in the table. I made the two columns a primary key. They are also both foreign keys referencing the ids in their respective tables. When I dragged the tables into the Object Relationship Designer it only showed a relationship line between either "Entry_Tag" and "Entry" or when I tried again between "Entry_tag" and "Tag".
The "Entry_tag" table should have a relationship with both "Tag" and "Entry".
How do I go about doing this?
In general, you can add a unique constraint on the table that includes both columns. In this case, including both of the columns in the primary key should have already done this. If you have relationships set up for each field to other tables, then I believe those relationships should be displayed in the query designer... I see no cause for this given the information you've provided - perhaps you need to post more information.
Create an UNIQUE INDEX to for entry_id and tag_id.
CREATE UNIQUE INDEX index_name ON table (entry_id, tag_id)