I am unable to send the String[] or List as an args to the "IN" operator. Can you please suggest me how to send the an input value for IN operator using crate java client.
it depends on what you are trying to achieve, IN only takes arbitrary length function parameters, which (assuming you want to use the '?' parameter substitution) does not take any array/list/other collection, but single values: For example select * from information_schema.tables where schema_name in (?, ?, ?); would be translated into select * from information_schema.tables where schema_name in ('a', 'doc', 'b'); when the parameters were ['a', 'doc', 'b']. See also: https://crate.io/docs/reference/sql/queries.html#in
If you want to check if a value was is an array, ANY() could work for you: https://crate.io/docs/reference/sql/queries.html#any-array - it should take an array as parameter.
Hope that helps!
Claus
Related
how are you?
I needed to store an array of numbers as JSONB in PostgreSQL.
Now I'm trying to calculate stats moments from this JSON, I'm facing some issues.
Sample of my data:
I already was able to convert a JSON into a float array.
I used a function to convert jsonb to float array.
CREATE OR REPLACE FUNCTION jsonb_array_castdouble(jsonb) RETURNS float[] AS $f$
SELECT array_agg(x)::float[] || ARRAY[]::float[] FROM jsonb_array_elements_text($1) t(x);
$f$ LANGUAGE sql IMMUTABLE;
Using this SQL:
with data as (
select
s.id as id,
jsonb_array_castdouble(s.snx_normalized) as serie
FROM
spectra s
)
select * from data;
I found a function that can do these calculations and I need to pass an array for that: https://github.com/ellisonch/PostgreSQL-Stats-Aggregate/
But this function requires an array in another way: unnested
I already tried to use unnest, but it will get only one value, not the entire array :(.
My goal is:
Be able to apply stats moment (kurtosis, skewness) for each row.
like:
index
skewness
1
21.2131
2
1.123
Bonus: There is a way to not use this 'with data', use the transformation in the select statement?
snx_wavelengths is JSON, right? And also you provided it as a picture and not text :( the data looks like (id, snx_wavelengths) - I believe you meant id saying index (not a good idea to use a keyword, would require identifier doublequotes):
1,[1,2,3,4]
2,[373,232,435,84]
If that is right:
select id, (stats_agg(v::float)).skewness
from myMeasures,
lateral json_array_elements_text(snx_wavelengths) v
group by id;
DBFiddle demo
BTW, you don't need "with data" in the original sample if you don't want to use and could replace with a subquery. ie:
select (stats_agg(n)).* from (select unnest(array[16,22,33,24,15])) data(n)
union all
select (stats_agg(n)).* from (select unnest(array[416,622,833,224,215])) data(n);
EDIT: And if you needed other stats too:
select id, "count","min","max","mean","variance","skewness","kurtosis"
from myMeasures,
lateral (select (stats_agg(v::float)).* from json_array_elements_text(snx_wavelengths) v) foo
group by id,"count","min","max","mean","variance","skewness","kurtosis";
DBFiddle demo
Hello I am getting error from my code, can someone help me please?
def query_builder(self, field_name, table_name, pkey, id):
queryx=sql.SQL("select {field} from {table} where {pkey} = %s",(id)).format(
field=sql.Identifier(field_name),
table=sql.Identifier(table_name),
pkey=sql.Identifier(pkey))
self.cur.execute(queryx.as_string(self.conn))
I'm going to assume you are using psycopg2.
If so the issues are, first:
"select {field} from {table} where {pkey} = %s",(id) ..."
Do not include the argument (id) in the string. Also this is not proper form for a single value in a tuple. Python requires it be (id,), note the comma.
Second:
self.cur.execute(queryx.as_string(self.conn))
Should be:
self.cur.execute(queryx, (id,))
The execute is where you supply the argument. Also the composable sql.SQL(...) can be passed directly to execute without being run through as_string. See here sql for more examples.
UPDATE
To use "*" there are two ways:
cur.execute(sql.SQL("select * from {table} where {pkey} = %s).format(table.sql.Identifier(table_name), pkey=sql.Identifier(pkey))
--OR
cur.execute(sql.SQL("select {field} from {table} where {pkey} = %s).format(field=sql.SQL("*"), table=sql.Identifier(table_name), pkey=sql.Identifier(pkey))
Warning, the second does allow for SQL injection as sql.SQL() does not escape values.
As to multiple fields the sql section of the docs has multiple examples. For instance:
If part of your query is a variable sequence of arguments, such as a comma-separated list of field names, you can use the SQL.join() method to pass them to the query:
query = sql.SQL("select {fields} from {table}").format(
fields=sql.SQL(',').join([
sql.Identifier('field1'),
sql.Identifier('field2'),
sql.Identifier('field3'),
]),
table=sql.Identifier('some_table'))
I would like to get the result of a query using rowMode="array" (as this is a potentially very large table and I don't want it formatted to object format) but I couldn't figure out how to pass in a array/list parameter for use in an IN operator.
const events = await t.manyOrNone({text: `select * from svc.events where user_id in ($1:list);`, rowMode: "array"}, [[1,2]]);
However, the above gives an error: syntax error at or near ":"
Removing the :list did not work either:
const events = await t.manyOrNone({text: `select * from svc.events where user_id in ($1);`, rowMode: "array"}, [[1,2]]);
Error: invalid input syntax for integer: "{"1","2"}"
I understand that this might be because I'm forced to use ParameterizedQuery format for rowMode="array" which does not allow those snazzy modifiers like :list, but this then leads to the question, if I were to use ParameterizedQuery format, then how do I natively pass in a Javascript array so that it is acceptable to the driver?
I guess an alternative formulation to this question is: how do I use arrays as parameters for ParameterizedQuery or PreparedStatements...
Answering my own question as I eventually found an answer to this issue: how to pass in arrays as params for use in the IN operator when using rowMode="array" | ParameterizedQuery | PreparedStatements.
Because this query is being parameterized in the server, we cannot use the IN operator, because the IN operator parameterize items using IN ($1, $2, $3...). Instead we need to use the ANY operator, where ANY($1) where for $1 an array is expected.
So the query that will work is:
const events = await t.manyOrNone({text: `select * from svc.events where user_id=ANY($1);`, rowMode: "array"}, [[1,2]]);
I have this query:
some_id = 1
cursor.execute('
SELECT "Indicator"."indicator"
FROM "Indicator"
WHERE "Indicator"."some_id" = %s;', some_id)
I get the following error:
TypeError: 'int' object does not support indexing
some_id is an int but I'd like to select indicators that have some_id = 1 (or whatever # I decide to put in the variable).
cursor.execute('
SELECT "Indicator"."indicator"
FROM "Indicator"
WHERE "Indicator"."some_id" = %s;', [some_id])
This turns the some_id parameter into a list, which is indexable. Assuming your method works like i think it does, this should work.
The error is happening because somewhere in that method, it is probably trying to iterate over that input, or index directly into it. Possibly like this: some_id[0]
By making it a list (or iterable), you allow it to index into the first element like that.
You could also make it into a tuple by doing this: (some_id,) which has the advantage of being immutable.
You should pass query parameters to execute() as a tuple (an iterable, strictly speaking), (some_id,) instead of some_id:
cursor.execute('
SELECT "Indicator"."indicator"
FROM "Indicator"
WHERE "Indicator"."some_id" = %s;', (some_id,))
Your id needs to be some sort of iterable for mogrify to understand the input, here's the relevant quote from the frequently asked questions documentation:
>>> cur.execute("INSERT INTO foo VALUES (%s)", "bar") # WRONG
>>> cur.execute("INSERT INTO foo VALUES (%s)", ("bar")) # WRONG
>>> cur.execute("INSERT INTO foo VALUES (%s)", ("bar",)) # correct
>>> cur.execute("INSERT INTO foo VALUES (%s)", ["bar"]) # correct
This should work:
some_id = 1
cursor.execute('
SELECT "Indicator"."indicator"
FROM "Indicator"
WHERE "Indicator"."some_id" = %s;', (some_id, ))
Slightly similar error when using Django:
TypeError: 'RelatedManager' object does not support indexing
This doesn't work
mystery_obj[0].id
This works:
mystery_obj.all()[0].id
Basically, the error reads Some type xyz doesn't have an __ iter __ or __next__ or next function, so it's not next(), or itsnot[indexable], or iter(itsnot), in this case the arguments to cursor.execute would need to implement iteration, most commonly a List, Tuple, or less commonly an Array, or some custom iterator implementation.
In this specific case the error happens when the classic string interpolation goes to fill the %s, %d, %b string formatters.
Related:
How to implement __iter__(self) for a container object (Python)
Pass parameter into a list, which is indexable.
cur.execute("select * from tableA where id =%s",[parameter])
I had the same problem and it worked when I used normal formatting.
cursor.execute(f'
SELECT "Indicator"."indicator"
FROM "Indicator"
WHERE "Indicator"."some_id" ={some_id};')
Typecasting some_id to string also works.
cursor.execute(""" SELECT * FROM posts WHERE id = %s """, (str(id), ))
If I have a jsonb column called value with fields such as:
{"id": "5e367554-bf4e-4057-8089-a3a43c9470c0",
"tags": ["principal", "reversal", "interest"],,, etc}
how would I find all the records containing given tags, e.g:
if given: ["reversal", "interest"]
it should find all records with either "reversal" or "interest" or both.
My experimentation got me to this abomination so far:
select value from account_balance_updated
where value #> '{}' :: jsonb and value->>'tags' LIKE '%"principal"%';
of course this is completely wrong and inefficient
Assuming you are using PG 9.4+, you can use the jsonb_array_elements() function:
SELECT DISTINCT abu.*
FROM account_balance_updated abu,
jsonb_array_elements(abu.value->'tags') t
WHERE t.value <# '["reversal", "interest"]'::jsonb;
As it turned out you can use cool jsonb operators described here:
https://www.postgresql.org/docs/9.5/static/functions-json.html
so original query doesn't have to change much:
select value from account_balance_updated
where value #> '{}' :: jsonb and value->'tags' ?| array['reversal', 'interest'];
in my case I also needed to escape the ? (??|) because I am using so called "prepared statement" where you pass query string and parameters to jdbc and question marks are like placeholders for params:
https://docs.oracle.com/javase/tutorial/jdbc/basics/prepared.html