Structured Query Language (SQL) is a language for managing data in relational database management systems. This tag is for general SQL programming questions; it is not for Microsoft SQL Server (for this, use the sql-server tag), nor does it refer to specific dialects of SQL on its own.

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2
votes
2answers
132 views

Combine union with distinct

Situation: I need distinct results from two tables, that both have duplicates. I would like to know if I should combine UNION and DISTINCT. Example 1 - Only use distinct SELECT DistinctValue FROM ...
1
vote
1answer
277 views

Should ORM data access methods be wrapped or used directly?

We're using an internally-built ORM. Each table is represented by a Model class, which inherits from a base model class that has a handful of methods like GetAll, GetWhere (to get rows with specified ...
12
votes
4answers
8k views

Why is SQL's BETWEEN inclusive rather than half-open?

Semi-open (or Half-Open, Half-Closed, Half-Bounded) intervals ([a,b), where xbelongs to the interval iff a <= x < b) are pretty common on programming, as they have many convenient properties. ...
31
votes
3answers
1k views

Why is most SQL written in YELLING? [duplicate]

On MySQL at least, the following two queries are functionally identical: select * from users limit 0, 1000; SELECT * FROM users LIMIT 0, 1000; However, most example sites and most developers I've ...
10
votes
6answers
4k views

Code formatting SQL queries

Should I break SQL queries in different lines? For example in the project I am working on, we have a query that is taking 1600 columns! 1600 + tab chars. I wrote queries like this: "SELECT bla , ...
-1
votes
1answer
506 views

SQLDatabase: Read a lot of data at once and process in memory or read the data when I need it?

I'm not sure how to approach this problem. I require a big chunk of data records from the SQL server. This chunk is based on variables, so I don't know before what records I need. I need to do a large ...
15
votes
3answers
36k views

Why do we need to put N before strings in Microsoft SQL Server?

I'm learning T-SQL. From the examples I've seen, to insert text in a varchar() cell, I can write just the string to insert, but for nvarchar() cells, every example prefix the strings with the letter ...
15
votes
7answers
716 views

To Domain or not to Domain

The SQL92 and SQL99 standards define CREATE DOMAIN DDL constructs. Not all databases support this, or have a different name for it (SQL Server has User Defined Types, for example). These allow one to ...
1
vote
1answer
35 views

Custom Domain or Attribute Reference Table or Both?

I'm designing my first real database and I'm weighing the pros and cons of how to enforce uniformity in my data. My first option is to create a custom domain and program my UI to only allow certain ...
1
vote
1answer
101 views

Database choice [closed]

I am working on a system where I am replacing and existing Cobol system with C#. For the database I have hit some requirement which I am having a hard time to find complete support for (tried SQLite ...
3
votes
3answers
223 views

Is there a 'standard' SQL that can replace all the various custom versions?

I have been writing SQL for over 10 years now. I am extremely proficient at it and have experience working in SQL Server, Oracle, MySQL, PostgreSQL, etc. While there are multiple standards out there, ...
15
votes
4answers
4k views

Databases: Where should the application logic run? [duplicate]

http://highscalability.com/blog/2010/11/9/facebook-uses-non-stored-procedures-to-update-social-graphs.html talks about how Facebook moved logic out of the database into the application in order to ...
6
votes
7answers
365 views

Logistically, how do you manage embedded SQL?

My current application is running into issues with its ORM, and we're relying on some pretty hairy SQL to express queries that the ORM can't. Are there best practices in terms of how to manage the ...
0
votes
0answers
63 views

An algorithm to implement SQL's ORDER BY with TOP/LIMIT or OFFSET/FETCH

Is there a general algorithm to implement SQL's ORDER BY with OFFSET/LIMIT more efficiently than sorting all the records? The algorithm for a simple TOP x is easy enough. It takes one full pass ...
2
votes
0answers
236 views

Separation of concerns between repository and service in DDD with complex entities

This probably seems as an example of opinion-based question, but I'm actually looking for rationale on how to decide correctly, I believe there is a correct solution that can be backed by solid ...
3
votes
2answers
273 views

Does ODBC require any run-time software beyond an .exe file to run against MySQL and ORACLE SQL? [closed]

I'm writing a software [under Windows] in C++ which later needs to be able to connect to both MySQL and ORACLE SQL. Now the software needs to be as simple for the user as possible. Now I'm ...
0
votes
2answers
185 views

Is it a bad practice to keep database schema scripts (DDL) and manipulation (DML) scripts in different modules

we have a project structure like the following "module-shared" module depends on "module-database" module and some other modules depend on "module-shared" but no other module depends on ...
2
votes
3answers
195 views

Managing database schema for a C++ app

I have an open source project (Cockatrice) that uses mysql for the server component. I'm planning some changes to the schema, but right now the only management I have is a script that runs the proper ...
0
votes
0answers
46 views

Database conceptual Question [duplicate]

When querying in database through PHP, is it good to open mysql connection before every query and close it as the query completes? or should we open the mysql connection as soon as the first query ...
0
votes
2answers
113 views

Best way to store revision information for quick access to view or revert changes

What I am looking for is the most optimal solution for storing content revisions in an MSSQL database. We have an application that allows users to make changes to small HTML content blocks similar to ...
0
votes
1answer
177 views

MongoDB: Replicate data in documents vs. “join”

Disclaimer: This is a question derived from this one. What do you think about the following example of use case? I have a table containing orders. These orders has a lot of related information ...
3
votes
2answers
104 views

An algorithm for finding subset matching criteria?

I recently came up with a problem which I would like to share some thoughts about with someone on this forum. This relates to finding a subset. In reality it is more complicated, but I tried to ...
0
votes
1answer
163 views

Refactoring a Single Rails Model with large methods & long join queries trying to do everything

I have a working Ruby on Rails Model that I suspect is inefficient, hard to maintain, and full of unnecessary SQL join queries. I want to optimize and refactor this Model (Quiz.rb) to comply with ...
0
votes
0answers
59 views

embedding LEFT OUTER JOIN within INNER JOIN

I am having some problems with one of the question's answered in the book "SQL FOR MERE MORTALS". Here is the problem statement Here is the Database Structure Here is the answer which I am ...
13
votes
3answers
2k views

Best way to organize SQL queries stored in your code ? (or should you?) [closed]

I am sure I am not the only one who gets frustrated when they see a page of code littered with SQL queries. The ActiveRecord and other ORM patterns help mitigate a good amount of SQL used in a ...
4
votes
2answers
342 views

Entity Framework with no direct table access

There are some similar questions I've found here, but none of them fully answer the question I'm asking. Similar questions: here and here In my company, I develop C# .NET applications and our Server ...
-4
votes
1answer
95 views

what data storage method should I use? [closed]

I am currently writing a program and among other things need to store data. The program listens to two computers talking to each other in a known protocol (the program know what protocol it is,the ...
0
votes
2answers
60 views

Changing an int to be a string in PHP / MySQL Schema

Background I'm trying to decide the best way to manage a change in requirements. Currently when an admin is assigned to a ticket, the ticket header record is given an owner and the ownerID field is ...
6
votes
5answers
2k views

What are the advantages to using SQL query builders?

Are there any advantages to using a query builder, rather than using raw SQL? E.g. $q->select('*') ->from('posts') ->innerJoin('terms', 'post_id') ->where(...) vs: SELECT * FROM ...
-1
votes
3answers
269 views

What constitutes a good Database System(Java / SQL related) [closed]

I've given this so much research but still couldn't come to my own conclusion, before continuing this question I would like to give you a rough idea of my current situation. I'm 18 years old and have ...
0
votes
2answers
62 views

Managing unique data correctly in SQL

Here in Brazil we have a personal identifier called CPF. This identifier has a sequence of 11 digits and is unique for each Brazilian citizen. Possibly in other countries there is something like that ...
2
votes
2answers
1k views

Database model for keeping track of likes/shares/comments on blog posts over time

My goal is to keep track of the popular posts on different blog sites based on social network activity at any given time. The goal is not to simply get the most popular now, but instead find posts ...
1
vote
1answer
302 views

Web-app filtering information client-side vs server-side?

I have a web-app that provides data (that is updated on an interval) for intranet users, who are able to filter information by location. I was having a discussion with a co-worker about whether that ...
0
votes
0answers
157 views

Javascript and SQL Lite (multi browser offline SQL/database query)

I'm in the elections division of my county and am trying to simplify a voter lookup method for our poll judges during election time. Currently we are using a clunky heavy application that the judges ...
17
votes
8answers
7k views

Using JOIN keyword or not

The following SQL queries are the same: SELECT column1, column2 FROM table1, table2 WHERE table1.id = table2.id; SELECT column1, column2 FROM table1 JOIN table2 ON table1.id = table2.id; And ...
0
votes
2answers
116 views

What is selection and what is projection

I am working on Android with the query() method of the ContentResolver class and it accepts 6 parameters, (uri,projection,selection,selectionArgs,sortOrder,cancellationSignal) for selection and ...
0
votes
1answer
159 views

Full Text Indexing Strategy for MS Excel Documents

Background As part of a broader application that allows users to search thousands of MS Office documents on a private network, I need to index and make searchable Microsoft Excel files. My basic ...
2
votes
1answer
668 views

When deciding a Primary Key, can I use Date part of a DateTime field

I'm designing a payroll system I have designed a database with several tables and this question is related to following tables EMPLOYEE (Employee_ID [pk], Name,... etc) LOCATION (Location_ID [pk], ...
2
votes
0answers
115 views

Serialized values or separate table, which is more efficient?

I have a Rails model email_condition_string with a word column in it. Now I have another model called request_creation_email_config with the following columns admin_filter_group:references ...
0
votes
1answer
231 views

Simplifying data search using .NET

An example on the asp.net site has an example of using Linq to create a search feature on a Music album site using MVC. The code looks like this - public ActionResult Index(string movieGenre, string ...
1
vote
1answer
159 views

Dynamic Query Generation : suggestion for better approaches [closed]

I am currently designing a functionality in my Web Application where the verified user of the application can execute queries which he wishes to from the predefined set of queries with where clause ...
56
votes
6answers
3k views

Is this a ridiculous way to structure a DB schema, or am I completely missing something?

I have done a fair bit of work with relational databases, and think I understand the basic concepts of good schema design pretty well. I recently was tasked with taking over a project where the DB was ...
0
votes
2answers
894 views

Large MySQL Batch Inserts From PHP: Run insert from script, or save as SQL file?

We have a large dataset that's current residing in many, many spreadsheets. I've been tasked with getting part of that data into our MySQL DB. When all is said and done, I will probably be inserting ...
-3
votes
3answers
2k views

How to not let anyone inspect elements of a webpage?

I was thinking to make some jQuery functions that will use ajax to control mysql. The whole idea is to make separate files of PHP (e.g query.php, addRow.php, update.php and delete.php) provide data to ...
1
vote
3answers
122 views

Store history in SQL database column

We have a database that stores the process/history of particular machines. What I mean by that is that we have "started", "updating", "shutdown", and so on for all the computers in the company. The ...
6
votes
4answers
354 views

Direct database manipulation an anti-pattern?

Recently I learned that some teams have moved all their database manipulation to the actual database through the use of stored procedures. I thought that was pretty clever, since the database becomes ...
11
votes
4answers
4k views

Maintaining referential integrity between a mobile client and a server

So I have a relatively simple system. A mobile client creates records in a sqlite database that I would like to have synced to a remote SQL server (that is shared with other mobile clients). So when I ...
1
vote
0answers
47 views

Track time spent on site

We are going to track user engagement (i.e. time spent on site, most viewed part/page of the system, etc). I don't see Google Analytics / MixPanel being able to do this, since we have to analyze ...
1
vote
2answers
244 views

Can I create a query which allows me to do this?

I have a table which stores user information, one column stores their ID. I had implemented four different attributes in the same table which stored a bit indicating which file operations that user ...
2
votes
1answer
274 views

Implementing Syncing between localStorage and SQL database?

I have made a simple web app, which runs completely offline - all data is saved in HTML5's localStorage. Now, I want the data to get synced with the server, so that the user is able to use the app on ...