I am using Google BigQuery and I got the following issue:
I have a table (A) like this:
| time | request |
|------------------------|-----------------|
|2019-09-24 11:10:00 UTC | fakewebsite.com |
|2019-09-24 11:10:00 UTC | realwebsite.com |
|........................|.................|
|2019-09-24 11:10:00 UTC | foobwebsite.com |
|2019-09-24 11:10:00 UTC | barrwebsite.com |
And another table (B) like this:
| blacklist |
|---------------|
| foo.com |
| ... |
| bar.com |
I want to make a query that will grab a modified version of the values inside the blacklist field of table B as follows:
SPLIT(NET.REG_DOMAIN(blacklist), CONCAT('.',NET.PUBLIC_SUFFIX(blacklist)))[OFFSET(0)] AS to_exclude --this will return only "foo" from "foo.com"
and then return all values from the request field of table A where none of the to_exclude was found.
I know how to do this for one value but I don't know how to do this for multiple. I am looking for something like the following:
#standardSQL
WITH tmp_blacklist AS
(SELECT
SPLIT(NET.REG_DOMAIN(blacklist), CONCAT('.',NET.PUBLIC_SUFFIX(blacklist)))[OFFSET(0)] AS to_exclude
FROM
mydataset.B)
SELECT
request
FROM
mydataset.A
WHERE
request NOT LIKE ("%value1%", "%value2%", ..., "%valuen%") -- I can't use OR along with the NOT LIKE since the values are too many and they will change.
The n values are the values of the tmp_blacklist table.
Also if I don't define the table with the WITH and I define it after the NOT LIKE I am going to get the following error: Scalar subquery produced more than one element which makes sense if LIKE expects only one element. But then again that's half of the job done if it get's fixed since I want the "%value%" and not just the value of the table.
Now I searched online for a way to do this and I found people saying that it can't be done and then some workarounds with combinations of LIKE and IN where people said it will be very slow if one of the tables grows to have tons of data(my case).
What is the best way to do this?
One method uses not exists:
SELECT a.request
FROM mydataset.A a
WHERE NOT EXISTS (SELECT 1
FROM tmp_blacklist bl
WHERE a.request LIKE CONCAT('%', bl.to_exclude, '%'
);
Note that this can be expensive. You might want to test constructing the exclusion string as:
'value1|value2|value3'
and then using regular expressions.
Related
Much ink has been spilled on the topic of sum types in SQL. The standard solutions are called absorption, separation, and partition; see, e.g.: https://www.inf.unibz.it/~montali/teaching/1415/dpm/slides/4.relational-mapping.pdf .
I want to ask about how to encode open sums. Normal sums allow a field to be one of a fixed set of several different types; with open sums, this set is not fixed.
The basic setup in our program: There is a list of "triggers," where each trigger can be one of many different things. Plugins can be written defining new trigger types, although the set of trigger types can be assumed to be known at compile time.
We want a table of all triggers.
Our current best idea:
Dynamically create a materialized view of the following form:
id | id_in_plugin_table | thing_in_main_program_it_refs | plugin_name
---------------------------------------------------------------------
1 | 27 | 8 | RegexTrigger
2 | 27 | 12 | RidiculouslyUnsafeCustomJSTrigger
This relation is automatically generated from the various plugin tables, each of which have their own ID and a thing_in_main_program_it_refs field.
For illustration, here's what the referenced tables may look like.
RegexTrigger table:
id | thing_in_main_program_it_refs | regex
---------------------------------------------------------------------
27 | 8 | hel*o
RidiculouslyUnsafeCustomJSTrigger
id | thing_in_main_program_it_refs | custom_js
---------------------------------------------------------------------
27 | 12 | (x) => isPrime(x.length())
Either use two roundtrips to lookup the plugin table and then query it, or combine them into a single SQL program which uses EXEC.
I'm happy with part 1, but not with part 2. Neither option sounds efficient, and the latter option uses EXEC.
So, we're looking for either (a) a better way to dynamically select a table in a query, or (b) a different approach to open sums.
I apologise if this has been asked before. I'm still not certain how to phrase my question for the title, so wasn't sure what to search for.
I have a hundred or so databases in the same instance, one for each of my customers, named for the customer, and they all have the same structure. I want to select a single result set that includes the database name along with the most recent date entry in one of the tables. I can pull the database names from sys.databases, but then for each database I want to select the most recent date from Events.Date_Logged so that my result set looks something like this:
_______________________________
| | |
|Cust_Name |Latest_Event |
|_______________|_______________|
| | |
|Customer1 |01/02/2020 |
|_______________|_______________|
| | |
|Customer2 |02/02/2020 |
|_______________|_______________|
| | |
|Customer3 |03/02/2020 |
|_______________|_______________|
I'm really struggling with the syntax though. I either get just a single row returned or every single event for each customer. I think my joins are as rusty as hell.
Any help would be appreciated.
What I suggest you do:
Declare a result variable (of type table)
Use a cursor to go over every database
Inside the cursor: do a select top 1 ... order by date desc to get the most recent record. Save this result in the result variable.
After the cursor print the result variable.
That should do the trick.
it is possible to store a function IN the table to automatically sum a group of columns and store the result in a final column?
ie:
+----+------------+-----------+-------------+------------+
| id | appleCount | pearCount | bananaCount | totalFruit |
+----+------------+-----------+-------------+------------+
| 1 | 300 | 60 | 120 | 480 |
+----+------------+-----------+-------------+------------+
where the column totalFruit is automatically calculated from the previous three columns and updated as the other columns update. in this specific application, there is ONLY going to be the one row. it would be spanky-handy to be able to just push the updated counts and then pull the calculated total out. i seem to recall reading about this ability somewhere, but for the life of me, i can't recall where... :poop:
if there is not way to do this, that's cool. but if there is... :smile:
TIA!
WR!
Yes, it is possible. But is it worth it? It is simple enough to do
SELECT ...
appleCount + pearCount + bananaCount AS totalFruit
...
See MariaDB Generated Columns for how to generate the extra column -- either as a real extra column or "virtual". What version of MariaDB?--There are a number of changes over time.
(MySQL users: 5.7.6 has a similar MySQL Generated Columns.)
My client wants the possibility to match a set of data against an array of regular expressions, meaning:
table:
name | officeId (foreignkey)
--------
bob | 1
alice | 1
alicia | 2
walter | 2
and he wants to do something along those lines:
get me all records of offices (officeId) where there is a member with
ANY name ~ ANY[.*ob, ali.*]
meaning
ANY of[alicia, walter] ~ ANY of [.*ob, ali.*] results in true
I could not figure it out by myself sadly :/.
Edit
The real Problem was missing form the original description:
I cannot use select disctinct officeId .. where name ~ ANY[.*ob, ali.*], because:
This application, stored data in postgres-xml columns, which means i do in fact have (after evaluating xpath('/data/clients/name/text()'))::text[]):
table:
name | officeId (foreignkey)
-----------------------------------------
[bob, alice] | 1
[anthony, walter] | 2
[alicia, walter] | 3
There is the Problem. And "you don't do that, that is horrible, why would you do it like this, store it like it is meant to be stored in a relation database, user a no-sql database for Document-based storage, use json" are no options.
I am stuck with this datamodel.
This looks pretty horrific, but the only way I can think of doing such a thing would be a hybrid of a cross-join and a semi join. On small data sets this would probably work pretty well. On large datasets, I imagine the cross-join component could hit you pretty hard.
Check it out and let me know if it works against your real data:
with patterns as (
select unnest(array['.*ob', 'ali.*']) as pattern
)
select
o.name, o.officeid
from
office o
where exists (
select null
from patterns p
where o.name ~ p.pattern
)
The semi-join helps protect you from cases where you have a name like "alicia nob" that would meet multiple search patterns would otherwise come back for every match.
You could cast the array to text.
SELECT * FROM workers WHERE (xpath('/data/clients/name/text()', xml_field))::text ~ ANY(ARRAY['wal','ant']);
When casting a string array into text, strings containing special characters or consisting of keywords are enclosed in double quotes kind of like {jimmy,"walter, james"} being two entries. Also when matching with ~ it is matched against any part of the string, not the same as LIKE where it's matched against the whole string.
Here is what I did in my test database:
test=# select id, (xpath('/data/clients/name/text()', name))::text[] as xss, officeid from workers WHERE (xpath('/data/clients/name/text()', name))::text ~ ANY(ARRAY['wal','ant']);
id | xss | officeid
----+-------------------------+----------
2 | {anthony,walter} | 2
3 | {alicia,walter} | 3
4 | {"walter, james"} | 5
5 | {jimmy,"walter, james"} | 4
(4 rows)
I have a table with data along the (massively simplified) lines of:
User | Value
-----|------
UsrA | 100
UsrA | 102
UsrB | 100
UsrA | 100
UsrB | 101
and, for reasons far to obscure to go into, I need to store the COUNT of each value in a table for future retrieval - ending up with something like
User | Value100Count | Value101Count | Value102Count
-----|---------------|---------------|--------------
UsrA | 2 | 0 | 1
UsrB | 1 | 1 | 0
However, there could be up to 255 different Values - meaning potentially 255 different ValueXCount columns. I know this is a horrible way to do things, but is there an easy way to get the data into a format that can be easily INSERTed into the destination table? Is there a better way to store the COUNT of values per user (unfortunately I do need to store this information; grabbing it from the source table each time isn't an option)?
The whole thing isn't very pretty, but you know that, rather than your table with 255 columns I'd consider setting up another table with:
User | Value | CountOfValue
And set a primary key over User and Value.
You could then insert the count's for given user/value combos into the CountOfValue field
As I said, the design is horrible and it feels like you would be better off starting from scratch, normalizing and doing counts live.
Check out indexed views. You can maintain the table automatically, with integrity and as a bonus it can get used in queries that already do count(*) on that data.