There is a some table Users with fields id, name, etc
I need to select some ids from Users and concatenate with some constant value A. For example, I want to get the following result:
id
--------------------------------------
someId-1
someId-2
someId-3
A
I can do it with plain sql in the following way:
SELECT id FROM users UNION ALL SELECT 'A';
How can I do it with slick?
For example:
val q: Query[UsersTable, Users, Seq] = ...
q.map(_.id).unionAll( "A" ) //TODO how to transform "A" to query or Rep
Well the answer how to create a Slick Query from a constant into is rather trivial: just use slick.lifted.Query.apply from companion object such as
q.map(_.id).unionAll( Query("A") )
Related
I have a model called Testing. The field called alias is a JSON field (a list really) and has values such as ["a", "b"] or ["d", "e"] and so on.
class Testing(db.Model):
__tablename__ = 'testing'
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(25))
alias = db.Column(JSON)
def __init__(self, name, alias):
self.name = name
self.alias = alias
In my flask view I grab a url parameter that I want to use to filter Testing to get all Testing objects in which the parameter value is in the alias json list. So for example if url_param_value="a" I want all the Testing objects where "a" is in alias. So the alias value of ["a", "b"] would be a hit in this example.
Here is my approach but its not working and I assume it has to do with seralization.
Testing.query.filter(Testing.alias.contains(url_param_val)).all()
I am getting the below error
NotImplementedError: Operator 'contains' is not supported on this expression
The name field is a JSON type, not an array type. JSON columns don't have a contains method, even if you happen to be storing array data (how would the database know?)
In Postgres, you can use json_array_elements to expand a JSON array to a set of JSON values; this will return one row per element:
select id, json_array_elements(alias) as val from testing;
id | val
---------+--------------------
1 | "a"
2 | "b"
You can use that as a subquery to select records that contain a matching value:
select t.id, t.name, t.alias, cast(q.val as varchar)
from testing t, (
select id, json_array_elements(alias) as val
from testing
) q
where q.id=t.id and cast(q.val as varchar) = '"a"';
In SQLAlchemy syntax:
subq = session.query(
Testing.id,
func.json_array_elements(Testing.alias).label("val")
).subquery()
q = session.query(Testing).filter(
cast(subq.c.val, sa.Unicode) == '"a"',
subq.c.id == Testing.id)
Warning: this is going to be very inefficient for large tables; you're probably better off fixing the types to match your data, and then creating appropriate indexes.
I'm using postgresql 11, I have a jsonb which represent a row of that table, it's look like
{"userid":"test","rolename":"Root","loginerror":0,"email":"superadmin#ae.com",...,"thirdpartyauthenticationkey":{}}
is there any method that I could gather all the "values" of the jsonb into a string which is separated by ',' and without the keys?
The string I want to obtain with the jsonb above is like
(test, Root, 0, superadmin#ae.com, ..., {})
I need to keep the ORDER of those values as what their keys were in the jsonb. Could I do that with postgresql?
You can use the jsonb_populate_record function (assuming your json data does match the users table). This will force the text value to match the order of your users table:
Schema (PostgreSQL v13)
CREATE TABLE users (
userid text,
rolename text,
loginerror int,
email text,
thirdpartyauthenticationkey json
)
Query #1
WITH d(js) AS (
VALUES
('{"userid":"test", "rolename":"Root", "loginerror":0, "email":"superadmin#ae.com", "thirdpartyauthenticationkey":{}}'::jsonb),
('{"userid":"other", "rolename":"User", "loginerror":324, "email":"nope#ae.com", "thirdpartyauthenticationkey":{}}'::jsonb)
)
SELECT jsonb_populate_record(null::users, js),
jsonb_populate_record(null::users, js)::text AS record_as_text,
pg_typeof(jsonb_populate_record(null::users, js)::text)
FROM d
;
jsonb_populate_record
record_as_text
pg_typeof
(test,Root,0,superadmin#ae.com,{})
(test,Root,0,superadmin#ae.com,{})
text
(other,User,324,nope#ae.com,{})
(other,User,324,nope#ae.com,{})
text
Note that if you're building this string to insert it back into postgresql then you don't need to do that, since the result of jsonb_populate_record will match your table:
Query #2
WITH d(js) AS (
VALUES
('{"userid":"test", "rolename":"Root", "loginerror":0, "email":"superadmin#ae.com", "thirdpartyauthenticationkey":{}}'::jsonb),
('{"userid":"other", "rolename":"User", "loginerror":324, "email":"nope#ae.com", "thirdpartyauthenticationkey":{}}'::jsonb)
)
INSERT INTO users
SELECT (jsonb_populate_record(null::users, js)).*
FROM d;
There are no results to be displayed.
Query #3
SELECT * FROM users;
userid
rolename
loginerror
email
thirdpartyauthenticationkey
test
Root
0
superadmin#ae.com
[object Object]
other
User
324
nope#ae.com
[object Object]
View on DB Fiddle
You can use jsonb_each_text() to get a set of a text representation of the elements, string_agg() to aggregate them in a comma separated string and concat() to put that in parenthesis.
SELECT concat('(', string_agg(value, ', '), ')')
FROM jsonb_each_text('{"userid":"test","rolename":"Root","loginerror":0,"email":"superadmin#ae.com","thirdpartyauthenticationkey":{}}'::jsonb) jet (key,
value);
db<>fiddle
You didn't provide DDL and DML of a (the) table the JSON may reside in (if it does, that isn't clear from your question). The demonstration above therefore only uses the JSON you showed as a scalar. If you have indeed a table you need to CROSS JOIN LATERAL and GROUP BY some key.
Edit:
If you need to be sure the order is retained and you don't have that defined in a table's structure as #Marth's answer assumes, then you can of course extract every value manually in the order you need them.
SELECT concat('(',
concat_ws(', ',
j->>'userid',
j->>'rolename',
j->>'loginerror',
j->>'email',
j->>'thirdpartyauthenticationkey'),
')')
FROM (VALUES ('{"userid":"test","rolename":"Root","loginerror":0,"email":"superadmin#ae.com","thirdpartyauthenticationkey":{}}'::jsonb)) v (j);
db<>fiddle
I have a details table with adeet column defined as jsonb[]
a sample value stored in adeet column is as below image
Sample data stored in DB :
I want to return the rows which satisfies id=26088 i.e row 1 and 3
I have tried array operations and json operations but it does'nt work as required. Any pointers
Obviously the type of the column adeet is not of type JSON/JSONB, but maybe VARCHAR and we should fix the format so as to convert into a JSONB type. I used replace() and r/ltrim() funcitons for this conversion, and preferred to derive an array in order to use jsonb_array_elements() function :
WITH t(jobid,adeet) AS
(
SELECT jobid, replace(replace(replace(adeet,'\',''),'"{','{'),'}"','}')
FROM tab
), t2 AS
(
SELECT jobid, ('['||rtrim(ltrim(adeet,'{'), '}')||']')::jsonb as adeet
FROM t
)
SELECT t.*
FROM t2 t
CROSS JOIN jsonb_array_elements(adeet) j
WHERE (j.value ->> 'id')::int = 26088
Demo
You want to combine JSONB's <# operator with the generic-array ANY construct.
select * from foobar where '{"id":26088}' <# ANY (adeet);
I store some data as JSON.
I want to flatten the data using jsonb_each.
The new column type is RECORD, but I don't how extract values from it.
SELECT T FROM (
SELECT json_each_text(skills::json->'prizes') FROM users) AS T;
The output is
jsonb_each
---------------------------------
(compliance,2)
(incentives,3)
(compliance,0)
(legal,3)
(legal,2)
(international-contributions,3)
The type is RECORD.
pg_typeof
-----------
record
I want to do an aggregate and GROUPBY, but I cannot figure out how to extract the first element(the string) and the second element (the value).
Here is a workaround I have found: JSON -> ROW -> JSON -> (string, integer) and then aggregate. But I am wondering if there is a shortcut and skip the ROW->JSON conversion.
SELECT U.key, AVG(U.value::int) FROM
(SELECT row_to_json(T)->'s'->>'key' AS key,
row_to_json(T)->'s'->>'value' AS value
FROM
(SELECT jsonb_each(skills::jsonb->'prizes') AS s
FROM users) AS T
) AS U
GROUP BY key;
Thanks a lot, #Arnaud, this seems like a not-very-common problem. I wasn't sure about json data structure after using row_to_json function, so I needed to validate that via:
SELECT row_to_json(T) FROM
(SELECT jsonb_each((data->'app_metadata'->>'results')::jsonb)
FROM temp) AS T;
And once I got the keys structure, I could replicate your approach:
SELECT row_to_json(T)->'jsonb_each'->>'key' as key, row_to_json(T)->'jsonb_each'->>'value' as value
FROM (select jsonb_each((data->'app_metadata'->>'results')::jsonb) FROM temp) AS T
I want to display the contents of the aggregated columns that is part of group by sql statement.
Example:
SELECT Shippers.ShipperName,COUNT(Orders.OrderID) AS NumberOfOrders FROM Orders
WHERE Orders.ShipperID=Shippers.ShipperID
GROUP BY ShipperName
In the above example the output gives me count as one of the result, whereas i need the aggregated orders.orderID actual values even. So say if one result count shows me 2. I need to know what are those two values which have been grouped. This result should be as another column in the same table.
try this with GROUP_CONCAT
SELECT Shippers.ShipperName,COUNT(Orders.OrderID) AS NumberOfOrders , array_agg(Orders.OrderID) as which_are_those FROM Orders
WHERE Orders.ShipperID=Shippers.ShipperID
GROUP BY ShipperName
array_agg returns an array, but you can CAST that to text and edit as needed (see clarifications, below).
Prior to version 8.4, you have to define it yourself prior to use:
CREATE AGGREGATE array_agg (anyelement)
(
sfunc = array_append,
stype = anyarray,
initcond = '{}'
);
or simply this:
SELECT Shippers.ShipperName,COUNT(Orders.OrderID) AS NumberOfOrders , string_agg(Orders.OrderID, ',') as which_are_those FROM Orders
WHERE Orders.ShipperID=Shippers.ShipperID
GROUP BY ShipperName