I am wondering if the following is achievable with Hana. I want to create a role/analyticPrivilege/user such that, the user can only view a specific set of rows of a view if a condition about the row is met.
Let's say I am having a view DEMO_VIEW, and here is what it looks like.
| foo | bar | location |
|-------|-------|----------|
| foo_0 | bar_0 | US |
| foo_1 | bar_1 | US |
| foo_2 | bar_2 | CA |
I want to create a role such that the user can view all rows where the location field == "US".
Is it possible?
Yes, that’s possible in a straightforward way:
use SAP HANA analytic privileges and assign it to users/roles accordingly.
Related
So I'm trying to model a basic recommended friend system based on user activity. In this model, people can join activities, and if two people aren't already friends and happen to join the same activity, thier recommendation score for eachother increases.
Most of my app uses Firebase, but for this system I'm trying to use BigQuery.
The current system I have in mind:
I would have this table to represnet friendships. Since its an undirected graph, A->B being in the table infers that B->A will also be in the table.
+-------+-------+--------------+
| User1 | User2 | TimeFriended |
+-------+-------+--------------+
| abc | def | 12345 |
| def | abc | 12345 |
| abc | rft | 3456 |
| ... | ... | ... |
+-------+-------+--------------+
I also plan for activity participation to be stored like so:
+------------+-----------+---------------+------------+
| ActivityId | CreatorID | ParticipantID | TimeJoined |
+------------+-----------+---------------+------------+
| abc | def | eft | 21234 |
| ... | ... | ... | ... |
+------------+---------- +---------------+------------+
Lastly, assume maybe there's a table that stores mutual activities for these recommended friends (not super important, but assume it looks like:)
+-------+-------+------------+
| User1 | User2 | ActivityID |
+-------+-------+------------+
| abc | def | eft |
| ... | ... | ... |
+-------+-------+------------+
So here's the query I want to run:
Get all the participants for a particular activity.
For each of these participants, get all the other participants that aren't their friend
Add that tuple of {participant, other non-friend participant} to the "mutual activites" table
So there are oviously a couple of ways to do this. I could make a simple BigQuery script with looping, but I'm not a fan of that because it'll result in a lot of scans and since BigQuery doesn't use indexes it won't scale well (in terms of cost).
I could also maybe use something like a subquery with NOT EXISTS, like something like SELECT ParticipantID from activities WHERE activityID = x AND NOT EXISTS {something to show that there doesn't exist a friend relation}, but then its unclear how to make this work for every participant at one go. I'd be finee if I can come to a solution who's table scans scale linearly with the number of participants, but I have the premonition that even if I somehow get this to work, every NOT EXISTS will result in a full scan per participant pair, resulting in quadratic scaling.
There might be something I can do with joining, but I'm not sure.
Would love some thoughts and guidance on this. I'm not very used to SQL, especially complex queries like this.
PS: If any of y'all would like to suggest another serverless solution rather than BigQuery, go ahead please :)
I'm trying design a system for an API that grants users access to a data table Data based on a permission table Permissions which is related to a group table Group. When a user makes a request for data (from the Data table), my API should only return rows from the Data table based on the values within the columns of the Data table that they have been granted to
view.
By default, a user will have no access to any rows when requesting data through my API. However, I'd like to grant access to Data based on values in columns.
For example If my Data table contains information about news articles and has columns title, news_source, posted_date, and other similar columns
id | title | news_source | posted_date | ...
-----+----------+-----------------------+-------------+------
1 | ... | NYTimes | 2019-12-30 |
2 | ... | BBC | 2019-12-30 |
3 | ... | BBC | 2019-12-30 |
4 | ... | Washington Post | 2019-12-30 |
5 | ... | NYTimes | 2019-12-30 |
6 | ... | NYTimes | 2020-01-01 |
7 | ... | Boston Globe | 2020-01-01 |
In this example, I'd like to grant a group access to get data only from NYTimes, posted after 2020-01-01, etc...
To do this, I've implemented the schema below
+-----+ +--------------+
|Group|<-------|Permission |
+-----+ +--------------+
|name | |group_id |
|... | |column_name |
+-----+ |text_value |
|date_value |
+--------------+
For Group, name is just the name of the group and the ellipse represents some other non-relevant columns. In Permissions, I have the foreign key to Group (group_id), the name of the column in the Data table that I'm accessing (column_name), and the value I'm granting access to (text_value or date_value depending on the column I'm referencing).
Right now, when a user makes a request for data, I run this SQL to apply the permissions (if the user's group has id = 1).
SELECT * FROM Data d
INNER JOIN Permission p1 ON p1.group_id = 1 AND p1.column_name = 'news_source' AND p1.text_value = d.news_source
INNER JOIN Permission p2 ON p2.group_id = 1 AND p2.column_name = 'posted_date' AND p2.date_value >= d.posted_date;
This will work, but I was wondering if there was a better more organized way to go about this. I feel there would be a lot of redundancy in this model across multiple groups with the same permissions.
I have a table that contains the history of Customer IDs that have been merged in our CRM system. The data in the historical reporting Oracle schema exists as it was when the interaction records were created. I need a way to find the Current ID associated with a customer from potentially an old ID. To make this a bit more interesting, I do not have permissions to create PL/SQL for this, I can only create Select statements against this data.
Sample Data in customer ID_MERGE_HIST table
| OLD_ID | NEW_ID |
+----------+----------+
| 44678368 | 47306920 |
| 47306920 | 48352231 |
| 48352231 | 48780326 |
| 48780326 | 50044190 |
Sample Interaction table
| INTERACTION_ID | CUST_ID |
+----------------+----------+
| 1 | 44678368 |
| 2 | 48352231 |
| 3 | 80044190 |
I would like a query with a recursive sub-query to provide a result set that looks like this:
| INTERACTION_ID | CUST_ID | CUR_CUST_ID |
+----------------+----------+-------------+
| 1 | 44678368 | 50044190 |
| 2 | 48352231 | 50044190 |
| 3 | 80044190 | 80044190 |
Note: Cust_ID 80044190 has never been merged, so does not appear in the ID_MERGE_HIST table.
Any help would be greatly appreciated.
You can look at CONNECT BY construction.
Also, you might want to play with recursive WITH (one of the descriptions: http://gennick.com/database/understanding-the-with-clause). CONNECT BY is better, but ORACLE specific.
If this is frequent request, you may want to store first/last cust_id for all related records.
First cust_id - will be static, but will require 2 hops to get to the current one
Last cust_id - will give you result immediately, but require an update for the whole tree with every new record
Is it possible to convert table with many columns to many tables of two columns without losing data?
I will show what I mean:
Let say I have a table
+------------+----------+-------------+
|country code| site | advertiser |
+------------+----------+-------------|
| US | facebook | Cola |
| US | yahoo | Pepsi |
| FR | facebook | BMW |
| FR | yahoo | BMW |
+------------+----------+-------------+
The number of rows = [(number of countries) X (number of sites)] and the advertiser column is a variable that gets a value from a list with a limited number of advertisers
Is it possible to transform the 3 columns table to several tables with 2 columns without losing data?
If create two tables likes this I will surly lose data:
+------------+------------+
|country code| advertiser |
+------------+------------+
| US | Cola,Pepsi |
|-------------------------|
| FR | BMW |
+-------------------------+
+------------+------------+
| site | advertiser |
+------------+------------+
| facebook | Cola,BMW |
|-------------------------|
| yahoo | Pepsi,BMW |
+-------------------------+
But is I add a third "connection" table this will it help keep all the data and have the ability to recreate the original table?
+--------------+--------------------+
| country code | site |
+--------------+--------------------+
| US | facebook,yahoo |
|-----------------------------------|
| FR | facebook,yahoo |
+-----------------------------------+
Whether the table you specify can be 'converted' into into multiple tables is determined by whether the table is in fifth normal form i.e. if and only if every non-trivial join dependency in it is implied by the candidate keys.
If the table is in fifth normal form then it cannot be converted into multiple tables. If the table is not in fifth normal form then it is in one of the four lower normal forms and can be further normalized into fifth normal form by 'converting' it into multiple tables.
A table's normal form is determined by the column dependencies. These are determined by the meaning of the table i.e. what this table represents in the real world. You have not stated what the meaning of this table is and so whether this particular table can be converted into multiple tables is unknown.
You need to understand the process of normalization and using this you should be able to determine if it is possible to convert table with many columns to many tables of two columns without losing data? based on the column dependencies in the table.
You may be looking for Entity-Attribute-Value. Certainly it is much better than your proposal for keeping field values organized and not requiring a search of the field to determine if a value is present.
I was playing with the following, but it's not there just yet.
ALTER TABLE `product_price` CHANGE `price` = `price` - 20;
What you're looking for is this:
UPDATE product_price SET price = price - 20;
So if your data looks like this:
| id | price |
|----|---------------|
| 1 | 25.20 |
| 2 | 26.50 |
| 3 | 27.00 |
| 4 | 24.25 |
It will turn it to this:
| id | price |
|----|---------------|
| 1 | 5.20 |
| 2 | 6.50 |
| 3 | 7.00 |
| 4 | 4.25 |
As tehvan pointed out in your comments, ALTER is used when you want to change the structure of the table. From the docs:
ALTER TABLE enables you to change the structure of an existing table. For example, you can add or delete columns, create or destroy indexes, change the type of existing columns, or rename columns or the table itself. You can also change the comment for the table and type of the table.
If you want to update information in any way you want to use the UPDATE statement.
As Paolo Bergantino mentioned, you tried to alter the structure of the table rather than the data contained in it. The SQL is made up of different parts, each responsible for something different. For defining your data structures (tables, views, etc.) you use the DDL (Data Definition Language). For manipulating data on the other hand, you use the DML (Data Manipulation Language).
This site shows the different parts of the SQL along with examples.