First of all I want to show how I made this in SQL:
Both the location and environment table will never contain more than those four rows. Each log can only be associated with 4 rows.
What I don't understand is how do I even start writing code that will take whatever the user has chosen, based on state switches etc in my UI and persist this?
Because when the user are done I want to store a "log-record", and the log-record may have location and environment rows associated with it. And what happen when the user let say, choose all the location rows, four times a row....does it add the location to the location "entity" every time? Would I end up with a lot of duplicated data? I would appreciate any help that can show me how to do this. Thank you!
Looks like you need three entities. You'll have Location and Environment entities that have whichever attributes they need, and a Log entity that has relationship with both Environment and Location. I think you're asking if instances of Location and Environment that happen to be the same will be duplicated in the core data store, or if multiple Log instances will relate to the same Location and Environment instances. Is that right? Answer: It's up to you. Say you want to save a Location instance that has a particular set of attributes. You could first search for one that has that exact set of attributes and associate it with your Log instance, or you could just create a new Location instance and not worry about the duplication. If you're storing zillions of these Log entries, the first plan might save a lot of space. If you're not saving them all that often, and particularly if the user can go back and change the data associated with a Log instance, you might want to use separate instances even if they happen to be the same.
Related
I'm a researcher in Loren Frank's lab at UCSF using datajoint and files in the nwb format. I made some changes to our code for defining entries in our ElectrodeGroup table, and was hoping to test those by deleting an entry in the table and regenerating it with the new code. I was able to delete the entry, but cannot repopulate it. In particular, when I run ElectrodeGroup.populate() or ElectrodeGroup.populate({"nwb_file_name": my_file_name}), no changes are made to the table. I confirmed that the electrode group I deleted and am trying to regenerate is defined in the original nwb file. I am seeking input on why the populate command seems to not be working here. Thanks in advance for any help!
This user also contacted our team through another channel. Sharing the solution below for future users, in reference to this schema. In short, the populate process is reserved for unique upstream primary keys.
Since the ElectrodeGroup's only upstream table dependency is Session, the make method will only be called if there are no electrode groups for that session. This is because from the perspective of DataJoint, the only 'guaranteed' knowledge about what should exist for this table is defined solely by the presence/absence of related upstream records. Since the 'new' primary 'electrode_group_name' attribute is defined by the ElectrodeGroup table itself, DataJoint doesn't know how many copies will be created by make, and so simply invokes make 1 time per Session, expecting the single make invocation to fully define all possible electrode_group_name values the table will use. If there is one value for that session, no work needs to be done, so no make() invocation occurs.
There are a couple possible solutions:
Model the electrode group explicitly, with a table defines the existence of an electrode group (e.g., ElectrodeGroupConfiguration). This ElectrodeGroup would then inherit primary keys from both Session and ElectrodeGroupConfiguration. The ElectrodeGroup make function would be adjusted to load that unique keys across upstream tables.
Adjust the make function to handle the partial insert/update case, and call the make function directly with the desired primary key when these kinds of 'abnormal' updates need to occur.
Method #1 is 'cleanest' w/r/t to the DataJoint data model (explicitly modeled data dependencies using make/populate), whereas #2 is slightly 'escaping' the DataJoint data model in a controlled way to achieve a desired schema/data result.
I have a problem in dealing with SAS Enterprise Guide that runs on the server of my client.
I do not have access to the libraries so, in order to use the datasets the only thing we can do is to store them on the local disk C: of the computer and drag them to SAS.
We can not create libraries because the server does not read local paths.
Once you drag a table, let's call it "mydata" in SAS, the table is automatically renamed "mydata9865" with random numbers at the end and "mydata" is its label.
If you right-click the table and go to properties, you can't find the name of the table, just the label.
The only way I found to check the real name of the dataset is to open the Query Builder and check the name in the code preview.
The problem is that I am dealing with tables of millions of records and the machine I am using is very slow, so whenever I want to open the Query Building, just to check the table's name, it takes sometimes even an hour.
I am not a SAS expert, so I am sure there is a smarter way to do so. Is it possible for instance to use the table by calling it with its label?
data mydata2;
set mydata;
run;
instead of
set mydata9865?
Or is there some place I can rapidly check the name of the table without going through the query builder?
I tried to google it but I can't find anything, I hope someone will be able to help me!
Thank you in advance
Hover the mouse pointer over a data node to see it's attributes. The data set name is the File name: value.
For example:
In this example I had renamed the nodes created by two different queries to be the same (doable:yes, smart:maybe not). NOTE: A data node Label: is not necessarily the same as it's underlying data set's label metadata.
Regarding
use the table by calling it with its label?
Two nodes can have the same label, and is a a situation that defeats this approach.
Use the COPY task to upload your data explicitly. It sounds like you're not adding your data to the projects properly so SAS automatically assigns a name, rather than if you explicitly import or load your data.
Problem solved! I should have simply upload the data to the server with Tasks->Data->Upload Data Sets to Server but I didn't know this task so I didn't know it was possible to do it at all!
https://communities.sas.com/t5/SAS-Enterprise-Guide/Importing-sas-data-sets-from-C-drive-into-SAS-EG-not-possible/td-p/135184
Thank you everybody for you help!
I want to know the exact difference between before_save and after_save. Now, I have read the documentation and I know the difference as per their name. But, I want to know the exact difference using real time entities. It would be great if you provide any example.
Before Save: The functionality written here will be called when you hit the save button and before the record is stored in the database.
Usage: Before save can be used normally. For a simple eg, lets say we can modify or add a field value just before the record goes into the database.
After Save: The functionality written here will be called when you hit the save button and after the record is stored in the database.
Usage: To help you understand the use of after_save, Lets take a scenario where we have Student record containing SL.No, Name, Course and Student No.
Lets say the SL.No is an auto incrementing field and Student no is the combination of the first letter of the Course and the SL.No.
Now here the auto incremented no wont exist untill the record is saved in the database, hence you wont get the required Student No unless the record is saved. So after_save here helps since the logic is executed after the record has been saved, to which an auto incremented no is already generated.
we recently changed one of the databases I develop on from Oracle accounts to LDAP login accounts and all went well for the front end used by the staff that access the system. However, we have a second method of entry restricted to admin staff that load the data onto the database and a lot of processing is called using the dbms_scheduler.
Most of the database tables have a created_by column which is defaulted to pick up their user name from a sys_context but when the data loads are run from dbms_scheduler this information is not available and hence the created_by columns all get populated with APP_GLOBAL.
I have managed to populate a Global Temporary Table (GTT) with the sys_context value and use this to populate the created_by from a stored procedure called by dbms_scheduler so my next logical step was to put this in a function and call it so it could be used throughout the system or even be referenced from a before insert trigger.
The problem is, when putting the code into a function the data from the GTT is not found. The table is set to preserve rows.
I have trawled many a site for an answer but have found nothing to help me can anyone here provide a solution?
The scheduler will be using a different session than the session that created the job - preserve rows will not make the GTT data visible in a different session.
I am assuming the created_by columns have a default value like nvl(sys_context(...),'APP_GLOBAL'). Consider passing the user name as a parameter to the job and set the context as the first step in the job.
A weekend off and a closer look at my code showed a fatal flaw in my syntax where the selection of data from the GTT would never happen. A quick tweak and recompile and all is well.
Jack, thanks for your help.
I keep seeing questions floating through that make reference to a column in a database table named something like DateLastUpdated. I don't get it.
The only companion field I've ever seen is LastUpdateUserId or such. There's never an indicator about why the update took place; or even what the update was.
On top of that, this field is sometimes written from within a trigger, where even less context is available.
It certainly doesn't even come close to being an audit trail; so that can't be the justification. And if there is and audit trail somewhere in a log or whatever, this field would be redundant.
What am I missing? Why is this pattern so popular?
Such a field can be used to detect whether there are conflicting edits made by different processes. When you retrieve a record from the database, you get the previous DateLastUpdated field. After making changes to other fields, you submit the record back to the database layer. The database layer checks that the DateLastUpdated you submit matches the one still in the database. If it matches, then the update is performed (and DateLastUpdated is updated to the current time). However, if it does not match, then some other process has changed the record in the meantime and the current update can be aborted.
It depends on the exact circumstance, but a timestamp like that can be very useful for autogenerated data - you can figure out if something needs to be recalculated if a depedency has changed later on (this is how build systems calculate which files need to be recompiled).
Also, many websites will have data marking "Last changed" on a page, particularly news sites that may edit content. The exact reason isn't necessary (and there likely exist backups in case an audit trail is really necessary), but this data needs to be visible to the end user.
These sorts of things are typically used for business applications where user action is required to initiate the update. Typically, there will be some kind of business app (eg a CRM desktop application) and for most updates there tends to be only one way of making the update.
If you're looking at address data, that was done through the "Maintain Address" screen, etc.
Such database auditing is there to augment business-level auditing, not to replace it. Call centres will sometimes (or always in the case of financial services providers in Australia, as one example) record phone calls. That's part of the audit trail too but doesn't tend to be part of the IT solution as far as the desktop application (and related infrastructure) goes, although that is by no means a hard and fast rule.
Call centre staff will also typically have some sort of "Notes" or "Log" functionality where they can type freeform text as to why the customer called and what action was taken so the next operator can pick up where they left off when the customer rings back.
Triggers will often be used to record exactly what was changed (eg writing the old record to an audit table). The purpose of all this is that with all the information (the notes, recorded call, database audit trail and logs) the previous state of the data can be reconstructed as can the resulting action. This may be to find/resolve bugs in the system or simply as a conflict resolution process with the customer.
It is certainly popular - rails for example has a shorthand for it, as well as a creation timestamp (:timestamps).
At the application level it's very useful, as the same pattern is very common in views - look at the questions here for example (answered 56 secs ago, etc).
It can also be used retrospectively in reporting to generate stats (e.g. what is the growth curve of the number of records in the DB).
there are a couple of scenarios
Let's say you have an address table for your customers
you have your CRM app, the customer calls that his address has changed a month ago, with the LastUpdate column you can see that this row for this customer hasn't been touched in 4 months
usually you use triggers to populate a history table so that you can see all the other history, if you see that the creationdate and updated date are the same there is no point hitting the history table since you won't find anything
you calculate indexes (stock market), you can easily see that it was recalculated just by looking at this column
there are 2 DB servers, by comparing the date column you can find out if all the changes have been replicated or not etc etc ect
This is also very useful if you have to send feeds out to clients that are delta feeds, that is only the records that have been changed or inserted since the data of the last feed are sent.