A SQL JOIN clause combines records from two or more tables in a relational database.
3
votes
1answer
14 views
SQL report of subscribers and their associated revenue
A user can have many subscriptions, and a subscription belongs to one plan. The plans table tells us a subscription's cost. Is the query below the correct one for ...
3
votes
1answer
101 views
Joining huge CSV files and splitting the result into batches
I've got ~20GB of data about the same subject, concatenated from small files of 16kB, each produced by different measurement equipment. They share some headers (on the example: B, D & E) and they ...
1
vote
0answers
25 views
3
votes
0answers
22 views
Updating ActiveRecord with text from a joined table
I have an Active Record update with the following data model:
TvMenuProfile has one rich_text_special
...
25
votes
5answers
3k views
Performance of a Foreach inside a Foreach iterating through a million records
I have two DataTables:
dt: is populated from a CSV file with over 1.7 million rows
dataStructure.Tables["AccountData"]: is ...
2
votes
1answer
20 views
Collating client ratings
The code is fetching records from a table called CSAT_SUMMARY_REPORTS[driver table] but due to the filters conditions applied which needs to be checked in another ...
5
votes
1answer
54 views
Report for a restaurant showing hourly sales information for a given timespan
I have been tasked with creating a report for a high-volume restaurant that shows hourly sales information for a given timespan. When generating this report for a single day, it's very quick, but when ...
4
votes
1answer
35 views
Fetching all the project's items for a specific project id
In the following query, I am fetching all the projects items with specific project id. At the same time, I am using a join in Select to fetch the delivered quantity of items of this project only. The ...
8
votes
2answers
56 views
Iterate list to map entries in Python
I have two files, namely:
File1:
CL1 AA XX YY ZZ SS \n
CL2 3_b AA
File2:
AA string1
AA string2
3_b string3
My ...
3
votes
1answer
72 views
Scanning multiple huge files in Python (follow-up)
I'm trying to implement an algorithm able to search for multiple keys through ten huge files in Python (16 million of rows each one). I've got a sorted file with 62 million of keys, and I'm trying to ...
3
votes
2answers
81 views
1
vote
1answer
29 views
Combining MySQL Left Join results [closed]
I'm trying to get the End result.
I already done it with 2 different queries. Is there a better way without UNION or which one is the best?
...
3
votes
2answers
67 views
Join JSON objects on common property
is there an easier/more efficient way to join two JSON objects on a common property than this? It's a GeoJSON file (basically an array of objects), and I want to pull in a property from another JSON ...
1
vote
1answer
40 views
Prices and contracts query
The query below is quite slow (taking about half a second). Any obvious things I could improve?
The PRICES table has about 21 million rows and 30 columns while ...
3
votes
1answer
820 views
Using LINQ to perform a LEFT OUTER JOIN in 2 DataTables (Multiples criteria)
I know that exists a lot of solutions about how to create an OUTER JOIN between two DataTables.
I created the following code in ...
2
votes
1answer
29 views
3
votes
1answer
33 views
1
vote
1answer
49 views
Archiving an SQL table of sessions and statistics
What my query is doing:
I have two SQL tables and I want to copy datarows from the one table to the other table. I am doing this for statistics. The source table includes all current ...
10
votes
1answer
94 views
Aggregating 2 lists by matching UniqueIDs
This Macro takes my company's 2 main sources of all-client data (each a data table in a separate worksheet) and aggregates them into a 3rd list, by matching a unique account number (for clients that ...
0
votes
2answers
510 views
MySQL JOIN to JSON array
I'm building a HTTP API and this part should return a JSON list of posts and their attached photos, like this:
...
0
votes
0answers
50 views
Health insurance claims query involving joins to fetch one column
General feedback is welcome, but I am especially wondering if there is a way to make things more efficient where I am joining an entire large table to gain use of one column (like when I join tables ...
2
votes
1answer
268 views
Returning IQueryable<T> from my repository in Repository pattern design pattern
I am developing an application based on Repository design pattern. What should be the return type from the Repository?
This is my UserRepository class:
...
2
votes
0answers
59 views
groupJoin() in Swift
I have created the following function in Swift for this library I am writing, which joins two arrays on a key (extracted using given closures), and then groups them by key in a ...
1
vote
0answers
106 views
Natural join row comparison
The intent of the function is to simply tell me whether or not two vectors contain the same values that have the same column names. At this point of my algorithm I'm just checking the whether or not I ...
5
votes
1answer
100 views
Fetching player data
I would like to select some information I have stored in my MySQL DB.
I have 2 tables named gameTable and playerTable. Now I ...
2
votes
2answers
151 views
Query using cross join or inner join
Please consider the following three tables that I am playing with in the image below:
I want to come up with a SQL Query which shows first_name, last_name, and the total amount of all orders for ...
3
votes
1answer
49 views
Join - order by vote-sum and check if user has voted
I have a vote and a comment table. Now I want to display all comments and order them by votes-sum. Sum because some votes can have a higher value than others.
Therefore I want to display if the user ...
2
votes
1answer
52 views
Select Queries From Parent-Child Tables Model
I have two tables (parent-child model): Loans & Transactions.
Each Loan row has multiple Transaction rows.
I want to select all rows from Loans together with most recent row from Transactions.
...
11
votes
4answers
2k views
LW, MTD, STD, YTD Sales… all in line and looking pretty
That's Last Week, Month-to-Date, Season-to-Date, and Year-to-Date sales.
I have a table-valued function for each one, that takes a date and returns all ...
7
votes
1answer
60 views
Joining collections… because it's fun
I'm working on a LinqEnumerable class (reviewable here), and I'm no Big-O expert and I'm pretty bad with algorithms, so I wonder what the complexity is for what ...
7
votes
3answers
258 views
Normalizing Invoices
I need to move data from one database to another, and since I don't have SSIS I'm doing this ETL with T-SQL scripts.
One of the source tables contains invoice details, and features a column that ...
3
votes
1answer
69 views
Merging totals from rows with duplicate IDs
I have the following query which updates the quantity when there are duplicate items and users (there should only ever be 2 duplicates), then deletes the row which doesn't get updated...
...
7
votes
3answers
6k views
Extracting data from text file in bash using awk, grep, head and tail
I've been writing bash script on and off, with pretty good results in terms of getting the job done. However, I'm worried that my script might be very ugly, as I am a beginner. I'm looking for advice ...
5
votes
1answer
58 views
I think I should use JOIN but I did this instead
Let me start by saying that I am brand new to PHP and MySQL.
I have two tables. One table is called domains and it contains the "rep" column which is an integer. It is related to the column "id" in ...
5
votes
1answer
76 views
Library database search with multiple JOINs is too slow
I have a MySQL query which runs very slowly. I've rewritten it many times but no improvements yet.
My current query for advanced search takes about 60 secs to complete. Any suggestions for improving ...
3
votes
1answer
130 views
Moonshot & `Thread.Abort` - dealing with the fallout
Recently, I encountered an anomaly in the manner by which a worker thread was terminated. It prompted me to do some searching and I realized that I was constructing thread code in a haphazard manner. ...
2
votes
1answer
137 views
Displaying subcategories of subcategories
I wanted to know if this code is safe against SQL injection or not?
Also do I need to mysqli_close if I already did the ...
11
votes
3answers
230 views
Geographic search
I have this table (inradar_ad) with almost 300k entries. I want to know why my query takes 160 secs to run.
I tried limiting with ...
4
votes
2answers
131 views
Data screening using Perl
Background information
I've been asked to write a little Perl script that allows genomic data to be screened against reference files in order to determine locations of specific mutations.
The input ...
7
votes
1answer
120 views
A faster way to combine two SQL table
I would like to give it a try and ask about my codes on here from now on to see if there are improvement for'em
this code is supposed to combine two sql tables into one.
...
2
votes
1answer
60 views
Join of two databases
This is the most basic code to join two tables in a database. For tables it uses a simple list. Solved this using brute force, sorting and using hashtable.
...
3
votes
2answers
268 views
5
votes
1answer
1k views
SQL cross join and multiple joins
Is there a way to improve this SQL query? It involves multiple cross join and joins.
I have 3 tables, and I want to compute the cardinal product:
...
0
votes
2answers
1k views
Make a MySQL SELECT and INNER JOIN faster
I have the following query which works as it should, but I'd like to know how I can make it run faster.
For info, tables cl, ...
