I am using Entity Framework. In my DB, I have a table (DOCMASTER) which is mapped in my model, and on occasion, has a backup from a different date created (e.g. DOCMASTER_10_01_2015). The mappings are identical, with the exception of the keys/constraints. These are not brought over with the backup.
I have an application with a dropdown that is filled with all of the tables in the DB that are of type "DOCMASTER". The user selects which table they would like to query from, and they search for a client in that particular version of the table.
What I would ideally like to do is remap my model to use the selected table instead of the mapped table, however when I do that using DbModelBuilder, it seems to want to remap all of the tables in that model, not just the one table. I receive the error "CodeFirstNamespace.CUSTOM1: : EntityType 'CUSTOM1' has no key defined. Define the key for this EntityType" wherein 'CUSTOM1' is my table name, but I receive this for all of my tables in the model.
I am debating just using a paramaterized query to query the selected table directly. Does anyone have any thoughts on this?
Related
We have two tables. One is normal users tables where we are storing the normal user information this table we can say as a base table. And another is user_staff table which is also having different table but with user_id as a reference to user table.
Virtually saying the users and user_staff are almost same set of data but we are keeping this in different table since user table having master data and staff table having user_staff data.
While we are indexing this data in solr, we would like to keep all these users and user_staff in a single collection but we have to keep an additional key in each collection to mention the type like master, sub-account, user. But if we are usig this in a single collection how we can keep a connection of users_staff to user table as we do in mysql in solr?
I'm currently solving this task: some data should be sent from AdventureWorks2012 to Anchor model tables on the same server in MsSQL.
This is my Anchor Model
At this point I have a pretty simple Integration Services project in Visual Studio and it looks like this.
Control flow:
For example Load_territories is:
The main requirement is to fill all tables of Anchor model tables in MsSQL but I'm constantly facing a problem: the amount of attributes in tables are different and some of them are repeating
At this picture in the second table basically TR_ID,TR_GRP_TR_ID, TR_TID_TR_ID, TR_TNM_TR_ID contain the same values from dwh_key but it's impossible to create a one-to-many relation between attributes. My tutor has recommended me to use Lookup but I cannot figure out how to implement them in this project
This may be considered as cheating, but if you insert data into the latest view rather than the separate 6NF tables all of those ID fields will be populated by underlying trigger logic. I suspect that this would defeat the purpose of using SSIS though, since you would effectively be loading attributes sequentially rather than in parallel.
Another option is to leave surrogate key management to the ETL tool. This would require that you switch the data type for your identities from integers to GUID:s. SSIS can then generate a GUID and you can then use that very same GUID to populate all the attributes. Note that the anchor would have to be loaded first, or you will get a foreign key violation.
The most common solution though, is to leave surrogate key management to the database (and use integers). You would have a step in which you populate the metadata column in the anchor with the desired number of new identities to be created. Using the metadata number you can then select the newly generated identities and merge them into your data flow. It doesn't matter which number gets assigned to which row. After that all attributes can be populated in parallel, including their ID columns.
Of course, if this is intended to be used for more than an initial load, you would also have to add steps to detect if the data you are loading is already known or not.
I can also recommend watching the video tutorial referenced in this blog post: https://clinthuijbers.wordpress.com/2013/06/14/ssis-anchor-modeling-example-tutorial/
I have a project that is using EF6 Database first mapped to a SQL database. This is all new so I control the EF model as well as the database schema.
I currently have a table that I'll call Vehicle for simplicity. I use a discriminator column to get subclass Entities Car and Truck. This all works fine.
Now I need to do a 'soft delete' and move any deleted vehicles to a VehicleHistory table. (After trying this w/ EF i will probably use a SQL transaction). This needs to be reviewable so I need this history table mapped as well, but I would like to keep it within the inheritance hierarchy so its easily reused in other classes.
My idea was to create 'vehiclecurrent' and 'vehiclehistory' tables with FK's to Vehicle for shared columns. i would then use TPT in EF to get 'carcurrent','carhistory', ect... derived from my TPH classes(so e.g. carhistory->car->vehicle). This is not working and I get Error 3034: "Entities w/ different keys are mapped to the same row"
So my question is basically how can I pull this off? Will this approach work and how, or is there another way to accomplish this? Thanks!
I am looking at a problem which would involve users uploading lists of records with various field structures into an application. The 2nd part of this would be to also allow the users to specify fields to capture information.
This is a step beyond anything ive done up to this point where i would have designed a static RDMS structure myself. In some respects all records will be treated the same so there will be some common fields required for each. Almost all queries will be run on these common fields.
My first thought would be to dynamically generate a new table for each import and another for each data capture field spec.Then have a master table with a guid for every record in the application along with the common fields and then fields that specify the name of the table the data was imported to and name of table with the data capture fields.
Further information (metadata?) about the fields in the dynamically generated tables could be stored in xml or in a 'property' table.
This would mean as users log into the application i would be dynamically choosing which table of data to presented to the user, and there would be a large number of tables in the database if it was say not only multiuser but then multitennant.
My question is are there other methods to solving this kind of varaible field issue, im i going down an unadvised path here?
I believe that EAV would require me to have a table defining the fields for each import / data capture spec and then another table with the import - field - values data and that seems impracticle.
I hate storing XML in the database, but this is a perfect example of when it makes sense. Store the user imports in XML initially. As your data schema matures, you can later decide which tables to persist for your larger clients. When the users pick which fields they want to query, that's when you come back and build a solid schema.
What kind is each field? Could the type of field be different for each record?
I am working on a program now that does this sorta and the way we handle it is basically a record table which points to a recordfield table. the recordfield table contains all of the fields along with the field name of the actual field in the database(the column name). We then have a recorddata table which is where all the data goes for each record. We also store a record_id telling it which record it is holding.
This is how we do it where if each column for the record is the same type, then we don't need to add new columns to the table, and if it has more fields or fields of a different type, then we add fields as appropriate to the data table.
I think this is what you are talking about.. correct me if I'm wrong.
I think that one additional table for each type of user defined field for the table that the user can add the fields to is a good way to go.
Say you load your records into user_records(id), that table would have an id column which is a foreign key in the user defined fields tables.
user defined string fields would go in user_records_string(id, name), where id is a foreign key to user_records(id), and name is a string, or a foreign key to a list of user defined string fields.
Searching on them requires joining them in to the base table, probably with a sub-select to filter down to one field based on the user meta-data, so that the right field can be added to the query.
To simulate the user creating multiple tables, you can have a foreign key in the user_records table that points at a table list, and filter on that when querying for a single table.
This would allow your schema to be static while allowing the user to arbitrarily add fields and tables.
I have a SQL Server as backend and use ms access as frontend.
I have two tables (persons and managers), manager is derived from persons (a 1:1 relation), thus i created a view managersFull which is basically a:
SELECT *
FROM `managers` `m`
INNER JOIN `persons` `p`
ON `m`.`id` = `p`.`id`
id in persons is autoincrementing and the primary key, id in managers is the primary key and a foreign key, referencing persons.id
now i want to be able to insert a new dataset with a form in ms access, but i can’t get it to work. no error message, no status line, nothing. the new rows aren’t inserted, and i have to press escape to cancel my changes to get back to design view in ms access.
i’m talking about a managers form and i want to be able to enter manager AND person information at the same time in a single form
my question is now: is it possible what i want to do here? if not, is there a “simple” workaround using after insert triggers or some lines of vba code?
thanks in advance
The problem is that your view is across several tables. If you access multiple tables you could update or insert in only one of them.
Please also check the MSDN for more detailed information on restrictions and on proper strategies for view updates
Assuming ODBC, some things to consider:
make sure you have a timestamp field in the person table, and that it is returned in your managers view. You also probably need the real PK of the person table in the manager view (I'm assuming your view takes the FK used for the self-join and aliases it as the ID field -- I wouldn't do that myself, as it is confusing. Instead, I'd use the real foreign key name in the managers view, and let the PK stand on its own with its real name).
try the Jet/ACE-specific DISTINCTROW predicate in your recordsource. With Jet/ACE back ends, this often makes it possible to insert into both tables when it's otherwise impossible. I don't know for certain if Jet will be smart enough to tell SQL Server to do the right thing, though.
if neither of those things works, change your form to use a recordsource based on your person table, and use a combo box based on the managers view as the control with which you edit the record to relate the person to a manager.
Ilya Kochetov pointed out that you can only update one table, but the work-around would be to apply the updates to the fields on one table and then the other. This solution assumes that the only access you have to these two tables is through this view and that you are not allowed to create a stored procedure to take care of this.
To model and maintain two related tables in access you don’t use a query or view that is a join of both tables. What you do is use a main form, and drop in a sub-form that is based on the child table. If the link master and child setting in the sub-form is set correctly, then you not need to write any code and access will insert the person’s id in the link field.
So, don’t use a joined table here. Simply use a form + sub-form setup and you be able to edit and maintain the data and the data in the related child table.
This means you base the form on the table, and not a view. And you base the sub-form on the child table. So, don't use a view here.