what is the mongodb equivalent of the MySQL query
SELECT username AS `consname` FROM `consumer`
As it was mentioned by sammaye, you have to use $project in aggregation framework to rename fields.
So in your case it would be:
db.consumer.aggregate([
{ "$project": {
"_id": 0,
"consname": "$username"
}}
])
Cool thing is that in 2.6.x version aggregate returns a cursor which means it behaves like find.
You might also take a look at $rename operator to permanently change schema.
Salvador Dali's answer is fine, but not working in meteor versions before 3.0.
I currently try meteor, and their build in mongodb is in version 2.
The way I solved this is like this:
var result = []:
db.consumer.forEach( function(doc) {
result.push({
consname:doc.username
});
});
Related
I have a json object like so:
{
_id: "12345",
identifier: [
{
value: "1",
system: "system1",
text: "text!"
},
{
value: "2",
system: "system1"
}
]
}
How can I use the XDevAPI SearchConditionStr to look for the specific combination of value + system in the identifier array? Something like this, but this doesn't seem to work...
collection.find("'${identifier.value}' IN identifier[*].value && '${identifier.system} IN identifier[*].system")
By using the IN operator, what happens underneath the covers is basically a call to JSON_CONTAINS().
So, if you call:
collection.find(":v IN identifier[*].value && :s IN identifier[*].system")
.bind('v', '1')
.bind('s', 'system1')
.execute()
What gets executed, in the end, is (simplified):
JSON_CONTAINS('["1", "2"]', '"2"') AND JSON_CONTAINS('["system1", "system1"]', '"system1"')
In this case, both those conditions are true, and the document will be returned.
The atomic unit is the document (not a slice of that document). So, in your case, regardless of the value of value and/or system, you are still looking for the same document (the one whose _id is '12345'). Using such a statement, the document is either returned if all search values are part of it, and it is not returned if one is not.
For instance, the following would not yield any results:
collection.find(":v IN identifier[*].value && :s IN identifier[*].system")
.bind('v', '1')
.bind('s', 'system2')
.execute()
EDIT: Potential workaround
I don't think using the CRUD API will allow to perform this kind of "cherry-picking", but you can always use SQL. In that case, one strategy that comes to mind is to use JSON_SEARCH() for retrieving an array of paths corresponding to each value in the scope of identifier[*].value and identifier[*].system i.e. the array indexes and use JSON_OVERLAPS() to ensure they are equal.
session.sql(`select * from collection WHERE json_overlaps(json_search(json_extract(doc, '$.identifier[*].value'), 'all', ?), json_search(json_extract(doc, '$.identifier[*].system'), 'all', ?))`)
.bind('2', 'system1')
.execute()
In this case, the result set will only include documents where the identifier array contains at least one JSON object element where value is equal to '2' and system is equal to system1. The filter is effectively applied over individual array items and not in aggregate, like on a basic IN operation.
Disclaimer: I'm the lead developer of the MySQL X DevAPI Connector for Node.js
I'm using mysql, when I try to run this query:
Order.findAll({
where: {
end_date: {
$ne: null,
},
},
});
The where clause it generates looks like this:
where: "`Order`.`end_date` = '2020-03-11 03:00:00'
I tried using $nin and $not, I also tried using a raw query, and I still get the same result.
I see there was a bug with sequelize and mysql a few versions behind, but it seems like it was fixed on 5.19.5, and I'm using v 5.21.5.
Mysql version is 5.7.29
Can anyone help me with this?
Edit: Found a solution somewhere else, all I had to do was use [Op.not]. In case anyone needs this as well.
That won't work with sequelize v5. Here is the way to go.
const Op = require('sequelize').Op
Order.findAll({
where: {
end_date: {
[Op.ne]: null,
},
},
});
You can read more about using operators here.
Deprecation warning here.
I have a column named params in a table named reports which contains JSON.
I need to find which rows contain the text 'authVar' anywhere in the JSON array. I don't know the path or level in which the text could appear.
I want to just search through the JSON with a standard like operator.
Something like:
SELECT * FROM reports
WHERE params LIKE '%authVar%'
I have searched and googled and read the Postgres docs. I don't understand the JSON data type very well, and figure I am missing something easy.
The JSON looks something like this.
[
{
"tileId":18811,
"Params":{
"data":[
{
"name":"Week Ending",
"color":"#27B5E1",
"report":"report1",
"locations":{
"c1":0,
"c2":0,
"r1":"authVar",
"r2":66
}
}
]
}
}
]
In Postgres 11 or earlier it is possible to recursively walk through an unknown json structure, but it would be rather complex and costly. I would propose the brute force method which should work well:
select *
from reports
where params::text like '%authVar%';
-- or
-- where params::text like '%"authVar"%';
-- if you are looking for the exact value
The query is very fast but may return unexpected extra rows in cases when the searched string is a part of one of the keys.
In Postgres 12+ the recursive searching in JSONB is pretty comfortable with the new feature of jsonpath.
Find a string value containing authVar:
select *
from reports
where jsonb_path_exists(params, '$.** ? (#.type() == "string" && # like_regex "authVar")')
The jsonpath:
$.** find any value at any level (recursive processing)
? where
#.type() == "string" value is string
&& and
# like_regex "authVar" value contains 'authVar'
Or find the exact value:
select *
from reports
where jsonb_path_exists(params, '$.** ? (# == "authVar")')
Read in the documentation:
The SQL/JSON Path Language
jsonpath Type
what is the difference between two mongo queries.
db.test.find({"field" : "Value"})
db.test.find({field : "Value"})
mongo shell accepts both.
There is no difference in your example.
The problem happens when your field names contain characters which cannot be a part of an identifier in Javascript (because the query engine is run in a javascript repl/shell)
For example user-name because there is a hyphen in it.
Then you would have to query like db.test.find({"user-name" : "Value"})
For the mongo shell there is no actual difference, but in some other language cases it does matter.
The actual case here is presenting what is valid JSON, and with myself as a given example, I try to do this in responses on this forum and others as JSON is a data format that can easily be "parsed" into native data structures, where alternate "JavaScript" notation may not be translated so easily.
There are certain cases where the quoting is required, as in:
db.test.find({ "field-value": 1 })
or:
db.test.find({ "field.value": 1 })
As the values would otherwise be "invalid JavaScript".
But the real point here is adhering to the JSON form.
You can understand with example: suppose that you have test collection with two records
{
'_id': ObjectId("5370a826fc55bb23128b4568"),
'name': 'nanhe'
}
{
'_id': ObjectId("5370a75bfc55bb23128b4567"),
'your name': 'nanhe'
}
db.test.find({'your name':'nanhe'});
{ "_id" : ObjectId("5370a75bfc55bb23128b4567"), "your name" : "nanhe" }
db.test.find({your name:'nanhe'});
SyntaxError: Unexpected identifier
In couchbase, I was wondering if there was a way - WITHOUT using a view - to iterate through database keys. The admin interface appears to do this, but maybe its doing something special. What I'd like to is make a call like this to retrieve an array of keys:
$result = $cb->get("KEY_ALBERT", "KEY_FRED");
having the result be an array [KEY_ALEX, KEY_BOB, KEY_DOGBERT]
Again, I don't want to use a view unless there's no alternative. Doesn't look like its possible, but since the "view documents" in the admin appears to do this, I thought i'd double-check. I'm using the php interface if that matters.
Based on your comments, the only way is to create a simple view that emit only the id as par of the key:
function(doc, meta) {
emit( meta.id );
}
With this view you will be able to create query with the various options you need :
- pagination, range, ...
Note: you talk about the Administration Console, the console use an "internal view" that is similar to what I have written above (but not optimized)
I don't know about how couchbase admin works, but there are two options. First option is to store your docs as linked list, one doc have property (key) that points to another doc.
docs = [
{
id: "doc_C",
data: "somedata",
prev: "doc_B",
next: "doc_D"
},
{
id: "doc_D",
data: "somedata",
prev: "doc_C",
next: "doc_E"
}
]
The second approach is to use sequential id. You should have one doc that contain sequence and increment it on each add. It would be something like this:
docs = [
{
id: "doc_1",
data: "somedata"
},
{
id: "doc_2",
data: "somedata"
}
...
]
In this way you can do "range requests". To do this you form array of keys on server side:
[doc_1, doc_2 .... doc_N]and execute multiget query. Here is also a link to another example
The couchbase PHP sdk does support multiget requests. For a list of keys it will return an array of documents.
getMulti(array $ids, array $cas, int $flags) : array
http://www.couchbase.com/autodocs/couchbase-php-client-1.1.5/classes/Couchbase.html#method_getMulti