join Questions
7
I have a problem with my query and I need to join two tables from different databases now my problem is how can I execute my query. I got my syntax format from here
Please visit first this link s...
Smithy asked 8/5, 2013 at 7:52
8
What's the essential difference(s) between pd.DataFrame.merge() and pd.concat()?
So far, this is what I found, please comment on how complete and accurate my understanding is:
.merge() can only ...
Rhombencephalon asked 7/7, 2016 at 22:12
5
Solved
I am using Spark 1.5.
I have two dataframes of the form:
scala> libriFirstTable50Plus3DF
res1: org.apache.spark.sql.DataFrame = [basket_id: string, family_id: int]
scala> linkPersonItemLes...
Whole asked 13/12, 2016 at 14:43
4
Is it possible to select only some columns from a table on a JOIN? (Any kind.)
7
Solved
Both these joins will give me the same results:
SELECT * FROM table JOIN otherTable ON table.ID = otherTable.FK
vs
SELECT * FROM table INNER JOIN otherTable ON table.ID = otherTable.FK
Is the...
Further asked 19/2, 2009 at 14:47
5
Solved
I have two MTS video files, each one 2 minutes long. I need to be able to join the files together and convert the format to MPEG4. I have a suitable command line for converting MTS to MP4 but don't...
Utterance asked 24/8, 2010 at 8:43
6
Solved
For example (not sure if most representative example though):
N <- 1e6
d1 <- data.frame(x=sample(N,N), y1=rnorm(N))
d2 <- data.frame(x=sample(N,N), y2=rnorm(N))
This is what I've got so...
Almund asked 1/12, 2010 at 7:47
5
Solved
I have this relation:
class Action < ApplicationRecord
has_many :actions_users
I tried to make a query like:
select *
from actions left outer join actions_users
on actions_users.action_id =...
Promisee asked 13/7, 2018 at 7:50
3
Solved
I am very new to Apache Spark. I would actually like to focus on basic Spark API specification and want to understand and write some programs using Spark API.
I have written a java program using Ap...
Roveover asked 5/2, 2015 at 7:47
6
Solved
SELECT airline, airports.icao_code, continent, country, province, city, website
FROM airlines
FULL OUTER JOIN airports ON airlines.iaco_code = airports.iaco_code
FULL OUTER JOIN cities ON airpor...
Riker asked 5/3, 2010 at 3:2
2
Solved
I have two IQueryables:
Ingredient:
IngId
Description
AvailableIngredient:
IngId
I already have an IQueryable for Ingredient:
var ingQuery = from i in context.Ingredients
select i;
How c...
Fishy asked 8/10, 2010 at 10:42
4
I have a very simple datamodel with a one-to-many relationship between video and comments:
class Video(models.Model):
url = models.URLField(unique=True)
.....
class Comment(models.Model):
title...
4
Solved
So here's the deal - I am currently using EF Core 3.1 and let's say I have an entity:
public class Entity
{
public int Id { get; set; }
public int AnotherEntityId { get; set; }
public virtual ...
Qualified asked 17/12, 2019 at 20:18
8
Solved
How costly are JOINs in SQL? And/or, what's the trade off between performance and normalization?
I've found a similar thread but it doesn't really capture the essence of what I'm trying to ask - so I've created a new thread.
I know there is a trade-off between normalization and performance, a...
Saxony asked 24/4, 2011 at 22:19
11
Solved
The following image is a part of Microsoft SQL Server 2008 R2 System Views. From the image we can see that the relationship between sys.partitions and sys.allocation_units depends on the value of s...
Werbel asked 21/4, 2012 at 6:33
8
Solved
If I have
SELECT * FROM Table1 t1
LEFT JOIN Table2 t2 ON t1.id = t2.id
WHERE t1.user='bob';
Does the WHERE clause run after the two tables are JOINED?
How do I make it so it runs prior to th...
Junejuneau asked 12/4, 2012 at 23:39
27
Solved
I'm wondering if this is possible in SQL. Say you have two tables A and B, and you do a select on table A and join on table B:
SELECT a.*, b.* FROM TABLE_A a JOIN TABLE_B b USING (some_id);
If tab...
6
Solved
I was looking at a few graphs to understand the difference between the joins, and I came across this image:
Maybe the problem is in representing this with Venn Diagrams.
But looking at the first j...
7
I'm trying to figure out how to use merge() to update a data frame.
Take for example the data frame foo
foo <- data.frame(index=c('a', 'b', 'c', 'd'), value=c(100, 101, NA, NA))
Which has the f...
4
I am attempting to use multiple columns in my join like this:
FROM Table1 t
INNER JOIN Table2 s ON t.number = s.number OR t.letter = s.letter
Both of these tables have several hundred thousand ...
5
Solved
I have a query that UNION's two somewhat similar datasets, but they both have some columns that are not present in the other (i.e., the columns have NULL values in the resulting UNION.)
The proble...
Set asked 16/6, 2009 at 22:42
9
Solved
Why does this work (returns "one, two, three"):
var words = ['one', 'two', 'three'];
$("#main").append('<p>' + words.join(", ") + '</p>');
and this work (returns "the list: 111"):
v...
Knighthood asked 19/1, 2010 at 4:46
6
Solved
I'm selecting two id columns but get error specified:
org.hibernate.QueryException: **query specified join fetching, but the owner of the fetched association was not present in the select list**
...
10
Solved
I have a table customer that stores a customer_id, email and reference. There is an additional table customer_data that stores a historical record of the changes made to the customer, i.e. when the...
9
I have 2 lists of objects:
people =
[{id: 1, name: "Tom", carid: 1},
{id: 2, name: "Bob", carid: 1},
{id: 3, name: "Sir Benjamin Rogan-Josh IV", carid: 2}];
cars=
[{id: 1, name: "Ford Fiesta",...
Tolidine asked 26/7, 2013 at 11:45
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