Suppose, there is a table users_customers which has three column user_id,customer_id and id. This table gives information about which user is assigned to which customer and vice-versa.
Now, I have a list of pair of user_id and customer_id. I know SQL query for to get row for a single pair of user_id and customer_id.
That is,
select * from users_customers where user_id in(uId) and customer_id in (cId).
But, how to get for all pairs in one go without executing query again and again for different pair. I am using postgresql 9.6. And, I will use alternate of this query in Spring Data JPA.
I would appreciate any help.
I'm not sure what your actual problem is, but you can use in with tuples:
where (user_id, customer_id) in ( (u1, c1), (u2, c2), . . . )
You can also pass in multiple values as an array.
Related
I think I have a table that lacks a true primary key and I need to make one in the output. I cannot modify the table.
I need to run a select query to generate a list of values (list_A), then take those values and query them to show all the records related to them. From those records, I do another select to extract a now visible list called list_B. From list_B, I can search them to reveal all the records related to the original list (list_A), with many of those records missing the values from list_A but still need to be counted.
Here's my process so far:
I declared a sequence called 'temp_key', which starts from 1 and increments by 1.
I add a field called 'temp_key' to the parent query, so that it will hopefully show which element of the original list_A sub-query the resulting records are related to.
I run into trouble because I don't know how to make the temp_key increment as the list_A sub-query moves from the beginning to end of all the values in the list.
SELECT currval(temp_key) AS temp_key, list_A, list_B
FROM table
WHERE list_B IN (SELECT DISTINCT list_B
FROM table
WHERE list_A IN (SELECT DISTINCT list_A
from table);
As it is now, the above query doesn't work because there seems to be no way to make the current value of temp_key increment upward as it goes through values from the list originally generated from the lowest level sub-query (list_A).
For example, there might be only 10 values in list_A. And the output could have 100s of records, all labeled 1 through 10, with many of those values missing values in the list_A field. But they still need to be labeled 1 through 10 because the values of list_B connect the two sets.
Maybe you can create a new primary key column first with the following code (concatenating row number with list_a):
WITH T AS (
SELECT currval(temp_key) AS temp_key, list_A, list_B,
CONCAT(ROW_NUMBER() OVER(PARTITION BY list_A ORDER BY list_B),list_A) AS Prim_Key
FROM table )
SELECT * fROM T
Then you can specify in the where clause what keys you want to select
Hello & thank you in advance.
I have an access db that has the following information about mammals we captured. Each capture has a unique ID, which is the capture table's primary key: "capture_id". The mammals (depending on species) have ear tags that we use to track them from year to year and day to day. These are in a field called "id_code". I have the sex of the mammal as it was recorded at capture time in another field called sex.
I want a query that will return all instances of an id_code IF the sex changes even once for that id.
Example: Animal E555 was caught 4 times, 3 times someone recorded this animal as a F and once as a M.
I've managed to get it to display this info by stacking about 5 queries on top of each other (Query for recaptured animals -> Query for all records of animals from 1st query -> Query for unique combo of id & sex (via just using those two columns & requiring "Unique Values") -> Query that pulls only duplicate id values from that last one and pulls back up all capture records of those ids). HOwever, this is clearly not the right way to do this, it is then not updateable (which I need since this is for data quality control) and for some reason it also returns duplicates of each of those records...
I realize that this could be solved two other ways:
Using R to pull up these records (I want none of this data to have to leave the database though, because we're working on getting it into one place after 35 years of collecting! And my boss can't use R and I'm seasonal, so I want him to just have to open a query)
Creating a table that tracks all animal id's as an animal index. However, this would make entering the data more difficult and also require someone to go back through 20,000 records and create a brand new animal id for every one because you can't give ear tags to voles & things so they don't get a unique identifier in the field.
Help!
It is quite simple to do with a single query. As a bonus, the query will be updatable, not duplicated, and simple to use:
SELECT mammals.ID, mammals.Sex, mammals.id_code, mammals.date_recorded
FROM mammals
WHERE mammals.id_code In
(select id_code from
(select distinct id_code, sex from [mammals]) a
group by id_code
having count(*)>1
);
The reason why you see a sub-query inside a sub-query is because Access does not support COUNT(DISTINCT). With any other "normal" database you would write:
SELECT mammals.ID, mammals.Sex, mammals.id_code, mammals.date_recorded
FROM mammals
WHERE mammals.id_code In
(select id_code
from [mammals]
group by id_code
having count(DISTINCT Sex)>1
);
I'm having a table with an id and a name.
I'm getting a list of id's and i need their names.
In my knowledge i have two options.
Create a forloop in my code which executes:
SELECT name from table where id=x
where x is always a number.
or I'm write a single query like this:
SELECT name from table where id=1 OR id=2 OR id=3
The list of id's and names is enormous so i think you wouldn't want that.
The problem of id's is the id is not always a number but a random generated id containting numbers and characters. So talking about ranges is not a solution.
I'm asking this in a performance point of view.
What's a nice solution for this problem?
SQLite has limits on the size of a query, so if there is no known upper limit on the number of IDs, you cannot use a single query.
When you are reading multiple rows (note: IN (1, 2, 3) is easier than many ORs), you don't know to which ID a name belongs unless you also SELECT that, or sort the results by the ID.
There should be no noticeable difference in performance; SQLite is an embedded database without client/server communication overhead, and the query does not need to be parsed again if you use a prepared statement.
A "nice" solution is using the INoperator:
SELECT name from table where id in (1,2,3)
Also, the IN operator is syntactic sugar built for exactly this purpose..
SELECT name from table where id IN (1,2,3,4,5,6.....)
Hoping that you are getting the list of ID's on which you have to perform a query for names as input temp table #InputIDTable,
SELECT name from table WHERE ID IN (SELECT id from #InputIDTable)
I want only the unique records in same or new table. And I want to do this with different tables (having duplicate records) in access database through same code.
The flow should be like:
input table ------VBA MODULE------> table with unique records
I am able to do this group by function but for that i have to use field names in query. But field names will differ from table to table.
Please help!
Just use query
SELECT DISTINCT * FROM MyAnyTable
How can i generate an ID value for every set of duplicate records as seen in the second table with ID column? In other words, how can I let the first table to look like the second table using SQL query?
Assume that first name and last name in the first table can appear in duplicates.
Each first name and last name can have one or many purchase yr and cost.
The given image is just a sample. Total records in table 1 can reach thousands.
I'm using Oracle SQL.
Note: I'm working with one table only that is the first one. The second table is what I want.
You can use the DENSE_RANK analytic function to assign ID's as below:
EDIT:
Simplified query to generate ID's.
SELECT
DENSE_RANK() OVER (ORDER BY First_Name, Last_Name) ID,
t.*
FROM Table1 t;
Reference:
DENSE_RANK on Oracle Database SQL Reference