Update: See the "Update" section below for the latest.
I have been working with Knex.js to build SQL queries in Node.js, and have the following code. This code works on a sort of graph data model (nodes and links), where there is a links table which has everything (links link to links). Given this code, I am wondering how I can make it one query instead of one query per attribute which is how it is now. The getTableName() function returns a string_links table for string values, and <x>_links tables for the other datatypes, while the "basic" links table is just called links.
Essentially how this works is, first query the top level where the parent_id is equal to some "type" ID, say we are querying "user" objects, the type would be "user". So let instance = ... is getting all the instance links from this user type. Then we go through each field of a query (a query for now is just boolean-valued map, like { email: true, name: true }). For each field of the query, we make a query to find all those nodes, linked off the instance, as so-called property links.
There are two types of properties, but don't need to go into too much detail on that. Essentially there are complex properties with audit trails and simple properties without audit trails. That is what is meant by the interactive branch in the logic.
How can I make this into one SQL query? The SQL query it prints out for an example is like this:
select "id" from "links" where "parent_id" = '47c1956bz31330c' and "name" = 'link' limit 1
select "value" from "string_links" where "parent_id" = (select "value" from "links" where "parent_id" = '47c1956bz31330cv' and "name" = 'name' limit 1) and "name" = 'value' limit 1
select "value" from "text_links" where "parent_id" = (select "value" from "links" where "parent_id" = '47c1956bz31330cv' and "name" = 'website' limit 1) and "name" = 'value' limit 1
select "value" from "integer_links" where "parent_id" = (select "value" from "links" where "parent_id" = '47c1956bz31330cv' and "name" = 'revenue' limit 1) and "name" = 'value' limit 1
select "value" from "boolean_links" where "parent_id" = '47c1956bz31330' and "name" = 'verified' limit 1
The original Node.js for Knex.js is here, but really I'm just concerned with how to write this as one regular SQL query, and I can figure out how to make it in Knex.js from there:
async function selectInteractiveInstance(user, name, query) {
const type = model.types[name]
const typeId = await baseSchemaController.selectType(name)
let instance = await knex.from(`links`)
.select('id')
.where('parent_id', typeId)
.where('name', 'instance')
.first()
// { id: 123, props: { ... } }
instance.props = {}
for (let field in query) {
let data = query[field]
let attrSchema = type[field]
const tableName = baseSchemaController.getTableName(attrSchema.type)
if (attrSchema.interactive) {
const query1 = knex
.from(`links`)
.select('value')
.where('parent_id', instance.link)
.where('name', field)
.first()
const record = await knex
.from(tableName)
.select('value')
.where('home', query1)
.where('name', 'value')
.first()
if (record) {
instance.props[field] = record.value
}
} else {
const record = await knex
.from(tableName)
.select('value')
.where('parent_id', instance.id)
.where('name', field)
.first()
if (record) {
instance.props[field] = record.value
}
}
}
return instance
}
The reason for asking is because the number of queries of this function is equal to the number of properties on the object, and I would like to avoid that, but not really that great at SQL yet. I don't see a straightforward or clear path on how to make this into one query, or know if it's possible.
It's also an issue for the following reason. If I want to grab 100 links, and their "fields" (in the primitive link tables), such that the primitive link values match a certain value, then you need to query all field tables simultaneously to see if the query can be satisfied.
Update
I finally landed on a query that works in the optimistic case:
select
"x"."id" as "id",
"s1"."value" as "name",
"s2"."value" as "inc_id",
"s3"."value" as "website",
"s4"."value" as "revenue",
"s5"."value" as "verified"
from "links" as "x"
inner join "links" as "c1" on "c1"."parent_id" = "x"."id"
inner join "string_links" as "s1" on "s1"."parent_id" = "c1"."value"
inner join "links" as "c2" on "c2"."parent_id" = "x"."id"
inner join "string_links" as "s2" on "s2"."parent_id" = "c2"."value"
inner join "links" as "c3" on "c3"."parent_id" = "x"."id"
inner join "text_links" as "s3" on "s3"."parent_id" = "c3"."value"
inner join "links" as "c4" on "c4"."parent_id" = "x"."id"
inner join "integer_links" as "s4" on "s4"."parent_id" = "c4"."value"
inner join "boolean_links" as "s5" on "s5"."parent_id" = "x"."id"
where "x"."parent_id" = '47c1956bz31330'
and "x"."name" = 'link'
and "c1"."name" = 'name'
and "s1"."name" = 'value'
and "c2"."name" = 'inc_id'
and "s2"."name" = 'value'
and "c3"."name" = 'website'
and "s3"."name" = 'value'
and "c4"."name" = 'revenue'
and "s4"."name" = 'value'
and "s5"."name" = 'verified'
This returns an object similar to what I am looking for, joining the same table several times, along with the primitive tables.
However, if any of the values are not linked (are socalled "null" in this context), then the inner join will fail and it will return nothing. How can I still have it return a subset of the object properties, whatever it can find? Is there anything like optional inner joins or anything like that?
Use LEFT JOIN and move possibly unsatisfied predicates to ON clause. Kind of
select
"x"."id" as "id",
"s1"."value" as "name",
"s2"."value" as "inc_id",
"s3"."value" as "website",
"s4"."value" as "revenue",
"s5"."value" as "verified"
from "links" as "x"
left join "links" as "c1" on "c1"."parent_id" = "x"."id" and "c1"."name" = 'name'
left join "string_links" as "s1" on "s1"."parent_id" = "c1"."value" and "s1"."name" = 'value'
left join "links" as "c2" on "c2"."parent_id" = "x"."id" and "c2"."name" = 'inc_id'
left join "string_links" as "s2" on "s2"."parent_id" = "c2"."value" and "s2"."name" = 'value'
left join "links" as "c3" on "c3"."parent_id" = "x"."id" and "c3"."name" = 'website'
left join "text_links" as "s3" on "s3"."parent_id" = "c3"."value" and "s3"."name" = 'value'
left join "links" as "c4" on "c4"."parent_id" = "x"."id" and "c4"."name" = 'revenue'
left join "integer_links" as "s4" on "s4"."parent_id" = "c4"."value" and "s4"."name" = 'value'
left join "boolean_links" as "s5" on "s5"."parent_id" = "x"."id" and "s5"."name" = 'verified'
where "x"."parent_id" = '47c1956bz31330'
and "x"."name" = 'link'
Related
I have a situation where two tables should be joined with multiple columns with or condition. Here, I have a sample of sql query but i was not able to convert it into linq query.
select cm.* from Customer cm
inner join #temp tmp
on cm.CustomerCode = tmp.NewNLKNo or cm.OldAcNo = tmp.OldNLKNo
This is how i have write linq query
await (from cm in Context.CustomerMaster
join li in list.PortalCustomerDetailViewModel
on new { OldNLKNo = cm.OldAcNo, NewNLKNo = cm.CustomerCode } equals new { OldNLKNo = li.OldNLKNo, NewNLKNo = li.NewNLKNo }
select new CustomerInfoViewModel
{
CustomerId = cm.Id,
CustomerCode = cm.CustomerCode,
CustomerFullName = cm.CustomerFullName,
OldCustomerCode = cm.OldCustomerCode,
IsCorporateCustomer = cm.IsCorporateCustomer
}).ToListAsync();
But this query doesn't returns as expected. How do I convert this sql query into linq.
Thank you
You didn't tell if list.PortalCustomerDetailViewModel is some information in the database, or in your local process. It seems that this is in your local process, your query will have to transfer it to the database (maybe that is why it is Tmp in your SQL?)
Requirement: give me all properties of a CustomerMaster for all CustomerMasters where exists at least one PortalCustomerDetailViewModel where
customerMaster.CustomerCode == portalCustomerDetailViewModel.NewNLKNo
|| customerMaster.OldAcNo == portalCustomerDetailViewModel.OldNLKNo
You can't use a normal Join, because a Join works with an AND, you want to work with OR
What you could do, is Select all CustomerMasters where there is any PortalCustomerDetailViewModel that fulfills the provided OR:
I only transfer those properties of list.PortalCustomerDetailViewModel to the database that I need to use in the OR expression:
var checkProperties = list.PortalCustomerDetailViewModel
.Select(portalCustomerDetail => new
{
NewNlkNo = portalCustomerDetail.NewNlkNo,
OldNLKNo = portalCustomerDetail.OldNLKNo,
});
var result = dbContext.CustomerMasters.Where(customerMaster =>
checkProperties.Where(checkProperty =>
customerMaster.CustomerCode == checkProperty.NewNLKNo
|| customerMaster.OldAcNo == checkProperty.OldNLKNo)).Any()))
.Select(customerMaster => new CustomerInfoViewModel
{
Id = customerMaster.Id,
Name = customerMaster.Name,
...
});
In words: from each portalCustomerDetail in list.PortalCustomerDetailViewModel, extract the properties NewNKLNo and OldNLKNo.
Then from the table of CustomerMasters, keep only those customerMasters that have at least one portalCustomerDetail with the properties as described in the OR statement.
From every remaining CustomerMasters, create one new CustomerInfoViewModel containing properties ...
select cm.* from Customer cm
inner join #temp tmp
on cm.CustomerCode = tmp.NewNLKNo or cm.OldAcNo = tmp.OldNLKNo
You don't have to use the join syntax. Adding the predicates in a where clause could get the same result. Try to use the following code:
await (from cm in Context.CustomerMaster
from li in list.PortalCustomerDetailViewModel
where cm.CustomerCode == li.NewNLKNo || cm.OldAcNo = li.OldNLKNo
select new CustomerInfoViewModel
{
CustomerId = cm.Id,
CustomerCode = cm.CustomerCode,
CustomerFullName = cm.CustomerFullName,
OldCustomerCode = cm.OldCustomerCode,
IsCorporateCustomer = cm.IsCorporateCustomer
}).ToListAsync();
var result=_db.Customer
.groupjoin(_db.#temp ,jc=>jc.CustomerCode,c=> c.NewNLKNo,(jc,c)=>{jc,c=c.firstordefault()})
.groupjoin(_db.#temp ,jc2=>jc2.OldAcNo,c2=> c2.OldNLKNo,(jc2,c2)=>{jc2,c2=c2.firstordefault()})
.select(x=> new{
//as you want
}).distinct().tolist();
I read most of the solutions here with similar questions and it did not solve my problem and I cannot find anything online that can help me.
I am trying to make query on condition where user_id = session user_id but I get error when I make INNER join
ambiguous column name
for this
public List<CartModelClass>getCarts1(){
SQLiteDatabase db = getReadableDatabase();
SQLiteQueryBuilder qb = new SQLiteQueryBuilder();
String[] sqlSelect = { "ID" , "user_id", "food_id", "quantity", "price", "origin", "destination","description","company_name","search_id"};
String sqltable2 = "OrderDetails LEFT JOIN OrderDetails WHERE user_id LIKE '%%' ";
qb.setTables(sqltable2);
Cursor c = qb.query(db,sqlSelect, null, null ,null ,null ,null);
final List<CartModelClass> result = new ArrayList<>();
if (c.moveToFirst()) {
do {
result.add(new CartModelClass(
c.getString(c.getColumnIndex("user_id")),
c.getString(c.getColumnIndex("food_id")),
c.getString(c.getColumnIndex("quantity")),
c.getString(c.getColumnIndex("price")),
c.getString(c.getColumnIndex("origin")),
c.getString(c.getColumnIndex("destination")),
c.getString(c.getColumnIndex("description")),
c.getString(c.getColumnIndex("company_name")),
c.getString(c.getColumnIndex("search_id"))
));
} while (c.moveToNext());
}
return result;
}
so I changed InnerJoin and made it just table where user_id like"%%" but I only get the last user_id who added to cart and show all data for all users
I want to show only added cart for user_id = session user_id so i can use it in here
loadListFood
private void loadListFood(){
sessionManager= new SessionManager(getActivity());
final Hashmap<String, String> user = sessionManager.getUserDetail();
user.get(USER_ID);
listdata = new Database(this.getContext.getCarts1());
for(CartModelClass order : listdata)
user_id = order.getUser_id
if(user.get(USER_ID).equals(user_id)){
listdata = new Database(this.getContext()).getCarts();
adapter = new CartAdapter(listdata, this.getContext());
recyclerView.setAdapter(adapter);
int total = 0;
for (CartModelClass order : listdata) {
total += (Integer.parseInt(order.getPrice())) * (Integer.parseInt(order.getQuantity()));
Locale locale = new Locale("en", "US");
NumberFormat fmt = NumberFormat.getCurrencyInstance(locale);
txtTotalPrice.setText(fmt.format(total));
}
}else {
Toast.makeText(getContext(), "No Cart Added", Toast.LENGTH_LONG).show();
}
}
You are self joining the table OrderDetails.
In this case you must set aliases to both copies of the table, like:
OrderDetails as o1 LEFT JOIN OrderDetails as o2 ...
Now in the ON clause you must qualify the column names properly, like:
ON o1.user_id = o2.something
If you don't, you get that error message, because the column name user_id could belong to either of the 2 copies of the table.
Also:
What is session user_id? Is it a column name?
If it is then the problem is that it contains a space in its name.
Enclose it in square brackets, so the statemnet should be:
OrderDetails as o1 LEFT JOIN OrderDetails as o2
ON o1.user_id = o2.[session user_id]
I have a table name doc_definition with a json column definition which has a format like:
[{
"id":"0",
"name:"Ques1"
},{
"id":"1",
"name:"Ques2"
},{
"id":"2",
"name:"Ques3"
}]
and another table doc which has another json column def_val with format as:
{
"0":{
"value":"Ans1"
},
"1":{
"value":"Ans2"
},
"2":{
"value":"Ans3"
}
}
I want to create a Postgres SQL query that gives the value of a corresponding question by matching the id field inside both json.
SO far I've come up with this:
SELECT json_array_elements(def.definition) ->> 'name' AS json_test
FROM document_definitions AS def
INNER JOIN documents AS doc
ON doc.document_definition_id = def.id
WHERE doc.id = 892 AND json_array_elements(def.definition) ->> 'name' = 'Ques2'
But this throws exception:
ERROR: argument of AND must not return a set
When i put the json_array_elements(def.definition) ->> 'name' = 'Ques2' in SELECT clause, it returns boolean value.
I dont know whats wrong then. Plz Help?
How about that query :
SELECT json_array_elements(def.definition) ->> 'name' AS json_test
FROM document_definitions AS def
INNER JOIN documents AS doc
ON doc.document_definition_id = def.id
WHERE doc.id = 892 AND (json_array_elements(def.definition) ::json->> 'name') = 'Ques2'
After many trial and errors, I've come up with this.
Plz let me know if I can improve this in any way.
SELECT definition_json.definition_value -> definition_json.def_value_id ->> 'value' AS definition_value
FROM (
SELECT json_array_elements(def.definition) ->> 'name' = 'Ques2' AS is_definition_present,
json_array_elements(def.definition) ->> 'id' AS def_value_id,
doc.definition_value, doc.id AS document_id, def.id AS definition_id
FROM document_definitions AS def
INNER JOIN documents AS doc
ON doc.document_definition_id = def.id
) AS definition_json
WHERE definition_json.is_definition_present = 't' AND definition_json.document_id = 892
I'm trying to find an object by checking for several of its relations.
Loan.joins(:credit_memo_attributes)
.where(credit_memo_attributes: {name: 'pr2_gtx1_y', value: '2014'})
.where(credit_memo_attributes: {name: 'pr1_gtx1_y', value: '2013'})
.where(credit_memo_attributes: {name: 'tx1_y', value: '2014'})
Calling to_sql on that gives:
"SELECT `loans`.* FROM `loans` INNER JOIN `credit_memo_attributes`
ON `credit_memo_attributes`.`loan_id` = `loans`.`id`
WHERE `credit_memo_attributes`.`name` = 'pr2_gtx1_y' AND `credit_memo_attributes`.`value` = '2014'
AND `credit_memo_attributes`.`name` = 'pr1_gtx1_y' AND `credit_memo_attributes`.`value` = '2013'
AND `credit_memo_attributes`.`name` = 'tx1_y' AND `credit_memo_attributes`.`value` = '2014'"
So, I'm checking for Loans that have credit_memo_attributes with all of those attributes. I know at least 1 of our 20,000 loans meets this criteria, but this query returns an empty set. If I only use 1 of the where clauses, it returns several, as I'd expect, but once I add even 1 more, it's empty.
Any idea where I'm going wrong?
Update:
Based on comments I believe you want multiple joins in your criteria. You can do that like this:
attr_1 = {name: 'pr2_gtx1_y', value: '2014'}
attr_2 = {name: 'pr1_gtx1_y', value: '2013'}
attr_3 = {name: 'tx1_y', value: '2014'}
Loan.something_cool(attr_1, attr_2, attr_3)
class Loan < ActiveRecord::Base
...
def self.something_cool(attr_1, attr_2, attr_3)
joins(sanitize_sql(["INNER JOIN credit_memo_attributes AS cma1 ON cma1.loan_id = loans.id AND cma1.name = :name AND cma1.value = :value", attr_1]))
.joins(sanitize_sql(["INNER JOIN credit_memo_attributes AS cma2 ON cma2.loan_id = loans.id AND cma2.name = :name AND cma2.value = :value", attr_2]))
.joins(sanitize_sql(["INNER JOIN credit_memo_attributes AS cma3 ON cma3.loan_id = loans.id AND cma3.name = :name AND cma3.value = :value", attr_3]))
end
If you look at the SQL generated (that you included in your question, thank you) you'll see that all those conditions are being ANDed together. There are NO rows for which name = 'pr2_gtx1_y' AND name = 'pr1_gtx1_y' (and so forth). So you are getting the result I would expect (no rows).
You can put all names and values into array like ids and years and pass those into where clause like this. Active Record will query all the values in the array.
Loan.joins(:credit_memo_attributes)
.where(credit_memo_attributes: {name: ids, value: years})
Personally I'm still learning active record, in this concern i don't think active record supports multiple where clauses.
Notice how the SQL version is returning your code: it is joining the requirements with an AND.
"SELECT `loans`.* FROM `loans` INNER JOIN `credit_memo_attributes`
ON `credit_memo_attributes`.`loan_id` = `loans`.`id`
WHERE `credit_memo_attributes`.`name` = 'pr2_gtx1_y' AND `credit_memo_attributes`.`value` = '2014'
AND `credit_memo_attributes`.`name` = 'pr1_gtx1_y' AND `credit_memo_attributes`.`value` = '2013'
AND `credit_memo_attributes`.`name` = 'tx1_y' AND `credit_memo_attributes`.`value` = '2014'"
Now, this is next to impossible. An Object.name can never be all pr2_gtx1_y, pr1_gtx1_y, and tx1_y. Same goes for the value attributes.
What you need here is an OR as opposed to the AND.
To this effect, try to change your query to the following:
Loan.joins(:credit_memo_attributes)
.where(
"credit_memo_attributes.name = ? and credit_memo_attributes.value = ?
OR credit_memo_attributes.names = ? and credit_memo_attributes.value = ?
OR credit_memo_attributes.name = ? and credit_memo_attributes.value = ?",
'pr2_gtx1_y', '2014',
'pr1_gtx1_y', '2013',
'tx1_y', '2014'
)
I am converting a SQL query to LINQ that creates a left join with 1-to-1 mapping, and it has to be in Method Syntax. I have been pulling off my hair trying to accomplish this to no veil. I can do it in Lambda Syntax. Below is the example query I am trying to run. They are not actual code. Would someone point out what I am doing wrong?
SQL:
SELECT item.*, item_status.*
FROM item
LEFT JOIN item_status
ON item.ID = item_status.itemID
AND item_status.FLAGGED = true
WHERE item.published_date > "2008-06-19"
LINQ:
var linq_query = (
from selected_item in item
join selected_item_status in item_status
on selected_item.ID equals item_status.itemID into joined
from item_status in joined.DefaultIfEmpty()
where item_status.FLAGGED = true
select new {selected_item, selected_item_status}).ToList();
The join ... into becomes a GroupJoin and the second from becomes a SelectMany:
var linq_query = Item
.GroupJoin(
item_status.Where(x => x.selected_item_status.FLAGGED), // EDIT: Where clause moved here.
selected_item => selected_item.ID,
selected_item_status => selected_item_status.itemID,
(selected_item, joined) => new
{
selected_item,
statuses = joined.DefaultWithEmpty(),
})
.SelectMany(x => x.statuses.Select(selected_item_status => new
{
x.selected_item,
selected_item_status,
}))
// EDIT: Removed where clause.
.ToList();
It looks like the Where makes the left outer join unnecessary, as null statuses will be filtered out anyway.
EDIT: No, upon reviewing the SQL it looks like your LINQ query is slightly incorrect. It should be:
var linq_query = (
from selected_item in item
join selected_item_status
in (
from status in item_status
where status.FLAGGED
select status)
on selected_item.ID equals item_status.itemID into joined
from item_status in joined.DefaultIfEmpty()
select new {selected_item, selected_item_status}).ToList();