I see a lot of people asking the question of how to convert a data table to List Of<>. I am trying to understand what are the reasons to convert from data table to List Of<> or when would be it be better to use the List Of<> instead of data table.
As I see it if I am retriving data from the database and can assign the data source to a grid, listbox etc why would I want to convert it to List Of<> and what would be an advantage of converting it to a List Of<> ?
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I would like to compare data between two tables say source and destination and output the difference,
the problem is there's a mapping table which stores the columns of source table and corresponding columns of destination.
For example,
Table: T_MAP
SourceTableName SourceTableColumns DestinationTable DestinationTableColumn
s_t1 s_t1_col1 d_t1 d_t1_col1
s_t1 s_t1_col2 d_t d_t1_col2
s_t2 s_t2_col1 d_t2 d_t2_col1
....
So the question is how to compare the data between two tables with the map table.
Current idea is using dynamic cursor to generate dynamic sql statement, then using minus+union all to compare data. But the performance may be a big problem.
Is there any thoughts?
Please help..
Thanks in advance.
I have joined some data from HDFS with some data from an Oracle DW, which is working fine, but I cant seem to add any new columns to this sheet. To add columns for calculated fields etc I have to duplicate the sheet and do it there - this doesn't seem overly efficient.
Am I doing something wrong here or can you not add columns to a join result sheet?
... but I cant seem to add any new columns to this sheet.
Right. It will not be possible to add columns to a JoinedSheet. It is a new data set containing columns from two or more sheets based on a key column which you defined.
... or can you not add columns to a join result sheet?
It will be necessary to reference these data as input for a new Worksheet by Duplicating Worksheet.
Another approach could be using datameer rest-api. You can get the content of the workbook in json format and add columns manually or by implementing a simple script, then update the workbook with changed json file.
I'm trying to build a star schema in Oracle 12c. In my case my data source is not a relational database but a single excel/csv file which is populated via a google form, which means I don't have any sort of reference from a source system such as auto incremental keys/ids. Now what would be the best approach to build a star schema given this condition?
File row sample:
<submitted timestamp>,<submitted by user>,<region>,<country>,<branch>,<branch location>,<branch area>,<branch type>,<branch name>,<branch private? yes/no value>,<the following would be all "fact" values (measurements),...,...,...
In case i wanted to build a "branch" dimension, how would I handle updates/inserts after the first load into the dimension table?
Thought solution so far:
I had thought of making a concatenated string "key" with the branch values, which would make it unique (underscore would be the "glue" to concatenate the values), eg:
<region>_<country>_<branch>_<branch location> as branch_key
I would insert all the distinct branches into a staging table, including they branch_key column for each one of them, then when trying to load into the dimension I could compare which key does not exists yet in my dimension table and then insert it. As for updates, I'm a bit stuck on how to handle that, I had thought of having another file mapping which branches are active having a expiration date column. Basically trying to simulate what I could do having the data in a database instead of CSV files.
This is all I can think of so far, do you have any other recommendations/ideas on how to implement this? Take on consideration that the data source cannot as in I have to read these csv files, since data is not stored anywhere else.
Thank you.
I have a Table full of players. Each of these players can have a list of Items that they own. What I need to do is store that list of items for each player. Each item has an ID which is unique.
What I want to do is store an array of these items as a field in the Player Table. Does anyone know how this could be accomplished?
You can either go database route and create table of "ItemId to PlayerId" and query all items for given player by ID.
Or you can serialize data in XML/byte array using default .Net serialization and than dump it in BLOB field of "playerId to PlayerBLOB" table (XML/text can also be stored as text field - will be more readable).
You can store it as a delimited text. BUT! store it as xml instead, this will allow you to store complex weapon list and configuration in a column.
I have a very large set of data on which I'm doing a great deal of post-query manipulation (sorting, filtering, etc etc). I would like do all this manipulation on an array of ActiveRecord objects that contains only the information necessary to the sorting, filtering, and paging, and then add the data necessary for display at the end.
For example, let's say I have a database with two tables: baseball_players and player_infos. The baseball_players table contains all of the interesting stuff (stats, team, name, birthday, etc etc etc). Player_infos contains player_id, player_rank, and player_position. I have 15000 players, and I want to find the numbers 100-150 of the best catchers of all times. I retrieve an array of all player_infos, filter to only catchers, sort by player_rank, and then retrieve records 100-150.
What is the best way to merge the resulting player_info records with their corresponding baseball_player records? Hash.merge would work perfectly, but I don't want to convert these objects to Hashes. Does ActiveRecord support something similar?
Note that I have a restriction where I cannot simply query the data using SQL - I have to manually sort and filter an object containing all 15000 player_info records.
I believe you are looking for ActiveRecord::Base#update.