I have an enum State which can contain values like CA, NY, etc.
If I have a table Users , with a column states that contains an array of State values, so for example {CA, NY} how can I write a query to count the users grouped by each State value? so for {CA, NY} that should count 1 for CA and 1 for NY
So If I had records like:
| id | states |
| -- | ------- |
| 1 | {CA,NY} |
| 2 | {CA} |
| 3 | {NV,CA} |
I would expect a query to output:
| State | count |
| ----- | ----- |
| CA | 3 |
| NV | 1 |
| NY | 1 |
The first piece of advice is to normalise your data. You are breaking 2nd Normal form by holding multiple pieces of information in a single column.
Assuming you can't change that, then you will need to SPLIT the data like this
enter link description here
and you can then COUNT() and group it.
Related
I am having a problem creating VIEWS with Snowflake that has VARIANT field which stores JSON data whose keys are dynamic and keys definition is stored in another table. So I want to create a VIEW that has dynamic columns based on the foreign key.
Here are my table looks like:
companies:
| id | name |
| -- | ---- |
| 1 | Company 1 |
| 2 | Company 2 |
invoices:
| id | invoice_number | custom_fields | company_id |
| -- | -------------- | ------------- | ---------- |
| 1 | INV-01 | {"1": "Joe", "3": true, "5": "2020-12-12"} | 1 |
| 2 | INV-01 | {"2":"Hello", "4": 1000} | 2 |
customization_fields:
| id | label | data_type | company_id |
| -- | ----- | --------- | ---------- |
| 1 | manager | text | 1 |
| 2 | reference | text | 2 |
| 3 | emailed | boolean | 1 |
| 4 | account | integer | 2 |
| 5 | due_date | date | 1 |
So I want to create a view for getting each companies invoices something like:
CREATE OR REPLACE VIEW companies_invoices AS SELECT * FROM invoices WHERE company_id = 1
which should get a result like below:
| id | invoice_number | company_id | manager | emailed | due_date |
| -- | -------------- | ---------- | ------- | ------- | -------- |
| 1 | INV-01 | 1 | Joe | true | 2020-12-12 |
So my challenge above here is I cannot make sure the keys when I write the query. If I know that I could write
SELECT
id,
invoice_number,
company_id,
custom_fields:"1" AS manager,
custom_fields:"3" AS emailed,
custom_fields:"5" AS due_date
FROM invoices
WHERE company_id = 1
These keys and labels are written in the customization_fields table, so I tried different ways and I am not able to do that.
So could anyone tell me if we can do or not? If we can please give me an example so it would really help.
You cannot do what you want to do with a view. A view has a fixed set of columns and they have specific types. Retrieving a dynamic set of columns requires some other mechanism.
If you're trying to change the number of columns or the names of the columns based on the rows in the customization_fields table, you can't do it in a view.
If you have a defined schema and just need to grab dynamic JSON properties, you may want to consider looking into Snowflake's GET function. It allows you to get any part of a JSON using a string for the path rather than using a literal path in the SQL statement. For example:
create temp table foo(v variant);
insert into foo select parse_json('{ "name":"John", "age":30, "car":null }');
-- This uses a literal path in the SQL to get to a JSON property
select v:name::string as first_name from foo;
-- This uses the GET function to get the value from a path in a string
select get(v, 'name')::string as first_name from foo;
You can replace the 'name' in the second parameter of the GET function with the value stored in the customization_fields table.
In SF, You will have to use a Stored Proc function to retrieve the dynamic set of columns
I have table which consist of 35,000 records in which half of the rows have name as null value
If the field has null value, i want to update the field with the value of username.
Can anyone help me with this ?
This is sample table
name | username | idnumber | type
----------------------------------------------
-- | jack | 1 | A
Mark | Mark | 2 | B
-- | dev | 3 | A
After update i want it to look like this
name | username | idnumber | type
----------------------------------------------
jack | jack | 1 | A
Mark | Mark | 2 | B
dev | dev | 3 | A
You seem to want:
update t
set name = username
where name is null;
Note that -- is not a typical representation of NULL values. You might consider <null> for instance.
I have a table (e.g. Users) in PostgreSQL database. Its size is relatively large (ca. 4 GB of data) and I would like to get a table/result consisting of single rows fulfilling the select query. This query shall be executed for each element in an array of strings (couple dozens of elements).
Example single select for one element:
SELECT * FROM "Users" WHERE "Surname" LIKE 'Smith%' LIMIT 1
Value between ' and %' should be an element of input array.
EDIT: It doesn't matter for me whether I get record no. 1 or 2 for LIKE 'Smith%'
How can I achieve this?
I tried to append query results to some array variable within FOREACH loop but with no success.
Example source table:
| Id | Name | Surname |
|---- |-------- |---------- |
| 1 | John | Smiths |
| 2 | Adam | Smith |
| 3 | George | Kowalsky |
| 4 | George | Kowalsky |
| 5 | Susan | Connor |
| 6 | Clare | Connory |
| 7 | Susan | Connor |
And for ['Smith', 'Connor'] the output is:
| Id | Name | Surname |
|----|-------|---------|
| 1 | John | Smiths |
| 5 | Susan | Connor |
In Postgres you can use the ANY operator to compare a single value to all values of an array. This also works with together with the LIKE operator.
SELECT *
FROM "Users"
WHERE "Surname" like ANY (array['Smith%', 'Connor%'])
Note that LIKE is case sensitive, if you don't want that, you can use ILIKE
This will show you the logic. Syntax is up to you.
where 1 = 2
start of loop
or surname like 'Array Element goes here%'
end of loop
I am new to working with databases and I want to make sure I understand the best way to add or remove data from a database without making a mess of any related data.
Here is a scenario I am working with:
I have a Tags table, with an Identity ID column. The Tags can be selected via the web application to categorize stories that are submitted by a user. When the database was first seeded; like tags were seeded in order together. As you can see all the Campuses (cities) were 1-4, the Colleges (subjects) are 5-7, and Populations are 8-11.
If this database is live in production and the client wants to add a new Campus (City) tag, what is the best way to do this?
All the other city tags are sort of organized at the top, it seems like the only option is to insert any new tags at to bottom of the table, where they will end up taking whatever the next ID available is. I suppose this is fine because the Display category column will allow us to know which categories these new tags actually belong to.
Is this typical? Is there better ways to set up the database or handle this situation such that everything remains more organized?
Thank you
+----+------------------+---------------+-----------------+--------------+--------+----------+
| ID | DisplayName | DisplayDetail | DisplayCategory | DisplayOrder | Active | ParentID |
+----+------------------+---------------+-----------------+--------------+--------+----------+
| 1 | Albany | NULL | 1 | 0 | 1 | NULL |
| 2 | Buffalo | NULL | 1 | 1 | 1 | NULL |
| 3 | New York City | NULL | 1 | 2 | 1 | NULL |
| 4 | Syracuse | NULL | 1 | 3 | 1 | NULL |
| 5 | Business | NULL | 2 | 0 | 1 | NULL |
| 6 | Dentistry | NULL | 2 | 1 | 1 | NULL |
| 7 | Law | NULL | 2 | 2 | 1 | NULL |
| 8 | Student-Athletes | NULL | 3 | 0 | 1 | NULL |
| 9 | Alumni | NULL | 3 | 1 | 1 | NULL |
| 10 | Faculty | NULL | 3 | 2 | 1 | NULL |
| 11 | Staff | NULL | 3 | 3 | 1 | NULL |
+----+------------------+---------------+-----------------+--------------+--------+----------+
The terms "top" and "bottom" which you use aren't really applicable. "Albany" isn't at the "Top" of the table - it's merely at the top of the specific view you see when you query the table without specifying a meaningful sort order. It defaults to a sort order based on the Id or an internal ROWID parameter, which isn't the logical way to show this data.
Data in the table isn't inherently ordered. If you want to view your tags organized by their category, simply order your query by DisplayCategory (and probably by DisplayOrder afterwards), and you'll see your data properly organized. You can even create a persistent View that sorts it that way for your convenience.
I have a table in which several indentifiers of a person may be stored. In this table I would like to create a single calculated identifier column that stores the best identifier for that record depending on what identifiers are available.
For example (some fictional sample data) ....
Table = "Citizens"
Id | LastName | DL-No | SS-No | State-Id-No | Calculated
------------------------------------------------------------------------
1 | Smith | NULL | 374-784-8888 | 7383204848 | ?
2 | Jones | JG892435262 | NULL | NULL | ?
3 | Trask | TSK73948379 | NULL | 9276542119 | ?
4 | Clinton | CL231429888 | 543-123-5555 | 1840430324 | ?
I know the order in which I would like choose identifiers ...
Drivers-License-No
Social-Security-No
State-Id-No
So I would like the calculated identifier column to be part of the table schema. The desired results would be ...
Id | LastName | DL-No | SS-No | State-Id-No | Calculated
------------------------------------------------------------------------
1 | Smith | NULL | 374-784-8888 | 7383204848 | 374-784-8888
2 | Jones | JG892435262 | NULL | 4537409273 | JG892435262
3 | Trask | NULL | NULL | 9276542119 | 9276542119
4 | Clinton | CL231429888 | 543-123-5555 | 1840430324 | CL231429888
IS this possible? If so what SQL would I use to calculate what goes in the "Calculated" column?
I was thinking of something like ..
SELECT
CASE
WHEN ([DL-No] is NOT NULL) THEN [DL-No]
WHEN ([SS-No] is NOT NULL) THEN [SS-No]
WHEN ([State-Id-No] is NOT NULL) THEN [State-Id-No]
AS "Calculated"
END
FROM Citizens
The easiest solution is to use coalesce():
select c.*,
coalesce([DL-No], [SS-No], [State-ID-No]) as calculated
from citizens c
However, I think your case statement will also work, if you fix the syntax to use when rather than where.