In relational database design, a primary key can uniquely identify each row in a table. A primary key comprises a single column or a set of columns.

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Setting the Relationship as a Continuous Line Without Changing the Qty INT into Primery Key on SQL

Now it is required to make the following database. In the following, if I tick the checkbox of "Identifying Relationship", the line will become continuous line but the key type will also be ...
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SqlServer: can one table's PK be the FK of two table's?

I have three tables project, users and proj_user. The PK of proj_user table is the FK of project and users table's pk e.g.(project_id,user_id) My question is, is it possible if the project_id and ...
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persistence entity with composite key

I have class named 'User'. It has the following properties firstname lastname mobile email pin I want to design a table or hibernate entity that will have unique email for each row; the same for ...
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Auto increment holes in primary key - any issues?

I have an application that is creating large holes in the auto incremented primary surrogate key to the table as it uses lots of INSERT ... ON DUPLICATE KEY UPDATE queries. I'm looking into changing ...
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Database relationship refresher

All, After several years of programming applications, I'm looking to refresh my understanding of databases. What I knew to begin with was fairly basic, and honestly, it's disappeared over time. I ...
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primary_key problem in MySql view

I have 3 tables. and I want to create a view. There is no problem about generating SQL qeury and creating a view. but when I want to use this view in my web app it says me (LIKE THIS): "your view's ...
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Should a surrogate key reflect one of my columns? [duplicate]

I currently have a column called LoadID which is a surrogate key that just increment by max()+1. I also have LoadNumber which always seems to have the exact same value of LoadID, since they will ...
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Difference between OID and Primary key

Although I understand basic difference that OID is external to the tuple and generated by the system and Primary key is inside the tuple and generated by the db designer, I want to understand why OID ...
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Converting UUID's from CHAR(32) to BIN(16)

I have a few questions relating to UUID's, but before I go on, let me explain our schema a bit, first, we're on MySQL 5.5 (Percona's version to be exact)... In each applicable table, we use a two ...
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Primary keys optimized for database sync

I am implementing lazy multi-master database synchronization in star shape network using SymmetricDS. I can not estimate the number of nodes, so I can't use simple auto-increment integers. Database ...
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Impact of additional int field as primary key

Directly to the point, at one time I have a table like this: create table item( item_id varchar(50), constraint pk_item1 primary key (item_id) } However from my discussion one day, there is ...
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Overcoming the HDD IOPS limits on a billion row table? Is getting SSD the only solution?

I have a table with this structure: CREATE TABLE `requests` ( `userid` int(11) NOT NULL, `messageid` int(11) NOT NULL, `queueid` int(11) NOT NULL AUTO_INCREMENT, `problem_id` int(3) NOT NULL, ...
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primary key: username+current time or serial

I need to choose a primary key, but I'm not sure what the best option would be. Currently I'm in a scenario where a user has machines (workers) calculating hashes. For each user I track the current ...
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How to retrieve pkey value in mysql/python on duplicate key update

I'm currently using _mysql library in python. it uses pkey(int, auto increment) value that's created when inserting data using function conn.insert_id() This is how the query is made. INSERT INTO ...
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513 views

Postgresql Retrieve / Find Primary Key Serial Autonumber field for Audit logs

I need to find the Primary Key field name in each of a number (approx 70) of tables to create audit logs. All the primary keys are type serial (auto incrementing integer) and all have the name in the ...
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SQL Server: performance of IDENTITY vs INT as primary key

The most important table of my database is about 300,000 records, and growing. More than 20 tables have a FK to it. Its primary key is a number, but for historical reasons is defined as nvarchar(6) ...
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What are performance benefits when using number type instead of using char/varchar?

From various posts, I have summarized about using number type instead of char/varchar for PK: If you choose char/varchar type for PK and your values are short (just some alpha numberic codes) then it ...