Before I start I need to say I know multi-valued fields are a bad way to store data. However, because of the data and what it will be used for it seemed the easiest way and this problem has been bugging me for a short while
I am building a database that has multiple different tables based on Candidates and their specialized job sector
I have multiple queries that take data from one table to another depending on inputted values
I have a table called TblClient, which holds all the client names
I have a table called TblCandidateSupport, within this table, I have a lookup field that holds multiple values from TblClient (only needed so I can see which candidate has been to which clients)
The problem I am having is when I run an append query to the values stored in the multi-valued field to another table called TblCandidateSupportAvailable.
I either get an error "An INSERT INTO query cannot contain a multi-valued field" or only get one value appending when I use.value.
The value that is appended from the TblCandidate will only ever be viewed.
What is the best way to carry the data across?
Related
I am working on a database that has one main table with the entry rows having an individual table for calculations.
So I have about 9 tables that have calculations /values in that are associated with an individual indicator field entry in my main table. I would like to link the calculation tables to the individual entry.
The subdatasheet allows me to do this. However, it populates all the entries with the same table which I do not want as one calculation table is only associated to one entry.
I can’t create one table for all calculations as they have different types of data and are calculated differently so I can’t link with regards to relationships.
The only solution I can think of is by populating a new field called “results calculations” and populate it with the title of the calculation table associated to the individual entry.
Is there another way I would love all the data to be as accessible in one table as simplified as possible.
(I am new to MS Access so any advice will be appreciated.)
The result of using subdatasheet
What I need to link to each indicator
I have a table that contains data from repeated experiments (for example, site A has one sample, and the lab processed the sample three times obtaining slightly different values). I need to average these results in a separate table, but what I have read on the Microsoft support site is that a query that pulls data into another table with a calculated field is not possible on Access.
Can I query multiple data points from one table into a single calculated field in another table? Thank you.
UPDATE
I ended up doing a lot of manual adjustments of the file format to create a calculated field in the existing table that averages each sites data, so my problem is, for my current purposes, solved. However I would still like to understand. Following up with you both, I think the problem was that I had repeated non-unique IDs between rows when I probably should have made data columns with unique variable names so that I could query each variable name for an average.
So, instead of putting each site separately on the y axis, I formatted it by putting the sample number for each site on the x-axis:
I was able to at least create a calculated field using this second format in order to create an average value for each site.
Would have there been a way to write a query using the first method? Luckily, my data set was not at all very hefty, so I could handle a reformat manually, but if the case were with thousands of data entries, I couldn't have done that.
Also, here is the link to the site I mentioned originally https://support.office.com/en-ie/article/add-a-calculated-field-to-a-table-14a60733-2580-48c2-b402-6de54fafbde3.
Thanks all.
First, I'll ask the question:
Is it possible to make a value's type 'dynamic' by creating different tables with different value types and use a simple join query to fetch the correct table based on the type specified in a column?
Here is the context:
I'm building a sort of page builder where I want the "modules" to be dynamic in the sense that I can create new modules without having to modify the database in any way.
I envision 4 entities:
A field, which represents a single value of a specific type, for example a text field or a checkbox;
An entry type, which represents a group of fields to be used for an entry. For example, Article = Title + Content + Image.
An entry, which is the content defined by the corresponding entry type.
A value, which contains the data for one field for one entry, defined by the field's value type.
For the 'value' entity, I was planning on using multiple tables for each "type of value". "value_text", "value_integer", "value_boolean", etc.
What I wanted to do (and I think it's an anti-pattern in relational database) was to grab a value in the fields table to select the proper "value" table.
Here is an image of the structure I envisioned:
(imgur) UML Diagram of DB
So I'm looking for a way to make a single query to fetch the correct value for each field of a specific entry (by ID).
This means I have to access the assigned entry_type, fetch all the fields related to that entry_type, then fetch the value of each of those fields from the value tables based on the column 'value_type' of the fields table.
If this is possible, how can I achieve this? If it's not possible, what would be the best way to tackle this problem:
Make a first query to retrieve the fields, then a query for each field to grab the correct value? This makes a lot of queries to get the values of a single entry...
Modify the structure of the database to a more efficient set of relations, taking into account everything is dynamic...
Get rid of the idea of using mutiple "value types" and stick to using a more common everything-is-serialized-text approach.
Also, as this is one of my first questions on StackOverflow, please let me know if I asked incorrectly and how I should formulate this in the future.
Thanks for all of you who even take the time to read this :)
I am pretty new to SSIS and BI in general, so first of all sorry if this is a newbie question.
I have my source data for the fact table in a csv, so I want to match the ids against the surrogate keys in lookup tables.
The data structure in the csv is like this
... userId, OriginStationId, DestinyStationId,..
What I am trying to accomplish is to match the data against my lookup table. So what I am doing is
Reading Lookup data using OLE DB Source
Reading my csv file
Sorting both inputs by the same field
Doing a left join by Id, in order to get the SK
This way, if there is no match (aka can't find the surrogate key) I can redirect that to a rejected csv and handle it later.
something like this:
(sorry for the spanish!)
I am doing this for each dimension, so I can handle each one with different error codes.
Since OriginStationId and DestinyStationId are two values from the same dimension (they both match against the same lookup table), I wanted to know if there's a way to avoid reading two times the data from the table (I mean, not to use two ole db sources to read twice the data from the same table).
I tried adding a second output to the sort but I am not allowed to. The same goes to adding another output from OLE DB Source.
I see there's an "cache option", is the best way to go ? (Although it would impy creating anyway another OLE DB source.. right?)
The third option I thought of was joining by the two fields, but since there is only one field in the lookup table (the same field) I am getting an error when I try to map both colums from my csv against the same column in my Lookup table
There are columns missing with the sort order 2 to 2
What is the best way to go for this ?
Or I am thinking something incorrectly ?
If something was not clear let me know and I'll update my question
Any time you wish you could have multiple outputs from a component that only allows one, all you have to do is follow that component with the Multicast component, whose sole purpose is to split a Data Flow stream into multiple outputs.
Gonzalo
I have just used this article on how to derive columns for a data warehouse building:- How to Populate a Fact Table using SSIS (part 1).
Using this I built a simple package that reads a CSV file with two columns that are used to derive separate values from the same CodeTable. The CodeTable has two fields Id and Description.
The Data Flow has two "Lookup" tasks. The first one joins the attribute Lookup1 against the Description to derive its Id. The second joins the attribute Lookup2 against the Description to derive a different Id.
Here is the Data Flow:-
Note the "Data Conversion" was required to convert the string attributes from the CSV file into "Unicode string [DT_WSTR]" so they could be joined to the nvarchar(50) description attribute in the table.
Here is the Data Conversion:-
Here is the first Lookup (the second one joins "Copy of Lookup2" to the Description):-
Here is the Data Viewer output with the to two derived Ids CodeTableFirstId and CodeTableSecondId:-
Hopefully I understand your problem and this is of use to you.
Cheers John
I'm creating a form in CodeIgniter that has a paired value- Companies, and CEOs. The idea is, while there is only one Company field with one CEO field below initially on the form, there is a button for me to create more pairs of Company-CEO fields. I have an idea for how to make that appear on the frontend, but I'm not quite sure which is the best way to store it on the backend.
I think in order to combine each Company and CEO field into one value for storing in the MySQL database, I could simply use CONCAT. However, I'm not sure if I should even bother creating such a value. In any case, how would I handle the fact that there are a variable number of Companies (and thus CEOs) for each record? Would I have to store Company and CEO within another value? How could such an array or tuple be handled in MySQL?
Point 1: Do not combine the values. It will give you headaches in code splitting and combining. Make two columns, one for company, one for CEO.
Point 2: In general, when using a database, any time you have a list it gets its own table.
The various JS libraries out there let you handle this with a grid.