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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Crow Feet notation and identifying -vs- non-identifying relationships

Is it possible to distinguish between identifying and non-identifying relationships using the Crow Feet notation? Case in point: In table Book, part of the book's Primary Key is a FK to the Author ...
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MySQL Subquery returns more than one row

I have a table namely tbl_plays. It has the following columns and data id(PK)| gameid | drawid | etc ---------------------------------------------- 1 | 1509 | 73 | ...
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Keys of a relation

I got relation: R = { (ABCDEF) , (A B F -> C, B C -> F, F -> A, F -> B, D E -> E, E -> D)} keys of this relation are: {BCE}, {EF} But i dont get it... why? Why not only {EF}.. it got less ...
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123 views

Can one part of a multi-column primary key be used across tables?

I want to use SQLite as file format for my app, a reporting program. Below is an idea of the kind of schema I'll use (just the first few tables). There will be one report per file and all tables are ...
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117 views

Proper implementation of child (derived) table PK/FK during single and multiple inheritance hard coded generalization physical data model

Below is an image of hard coded generalization UML logical model of entities. I'd like to implement these classes as tables in a physical data model. Two derived classes/entities (Class2 and ...
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166 views

Are these custom module Drupal tables lacking foreign keys? mysqldump with table structures without data is included

I am troubleshooting a some tables in MySQL used by a custom Drupal module. Documentation for these tables is poor so I used mysqldump to get the structures in the Drupal database without the data. I ...
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Is it possible to change the data-type of a primary key column in SQL Azure? [duplicate]

Possible Duplicate: How can I alter an existing Primary Key on SQL Azure? OK, so say I have a table: 'Contact' and a primary key: 'ContactID'. The primary key is an INT but I want to ...
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5answers
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How should I save apache logs into a mysql table?

This is a php script to view apache logs. I want to save apache logs into a mysql database. Then add some rules for tagging urls using mysql REGEXP search, like: SET tag='some tag' WHERE url REGEXP ...
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3answers
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Reset Key Names to Defaults?

I'm working with some tables/columns that were renamed at some point, but the names of the primary/foreign keys are still based on the previous names. In SSMS is there any (preferably automatic) way ...
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2answers
4k views

MySQL - Autoincrement does not increment sequentally if last row was deleted

I have a table which contains an auto incremented primary key id. If I delete the last row (highest id, for exampe id = 6) and insert a new row, the new id starts at 7. Which paramater I have to ...
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1answer
118 views

Use surrogate or natural PK if a row is uniquely identified by two or more columns?

I am having a hard time choosing between natural and surrogate PK for my database table. The database is for a ranking system for an MOBA game. Here is more or less what I would do if I were to go ...
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258 views

Maintain table with too many insert

I have to create a table. Its size is going to increase very fast. Is there going to be any issue if many insert queries are fired at the same instant as mentioned here - User autoincrement ID for ...
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1answer
60 views

Create relationship between two tables with composite primary key

I've created a table [t1] with two fields and a composite primary key, show in below: create table t1( id int, name nchar(10), primary key(id,name) ); I want to create a second table ...
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2answers
67 views

What and How is the ID antipattern?

What is the ID antipattern and why / under which circumstances is it considered an antipattern? The id antipattern is having a unique ID column in each table. The ID is generated for each new ...
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4answers
91 views

SqlServer: can one table's PK be the FK of other two table's? [duplicate]

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 for the project_id and ...
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1answer
65 views

Batch converting indexes to keys [closed]

I have a legacy MS SQL Server database where all the primary and foreign keys were created as indexes. I am developing the new version of our software with Entity Frameworks, which I have learned ...
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3answers
605 views

Performance of primary key IDs with gaps (but in sequential order)

I know that having non-sequential IDs is bad for index performance. But assuming all my IDs are created in correct order, but with large gaps: i.e: 154300000 283700000 351300000 464200000 ...will ...
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1k views

Can a surrogate key and a primary key be in the same table?

For example we have: Surrogate key: ABC123 Primary key: 1 Name: James Is this legit in a Data Warehouse table?
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1k views

The four properties of a primary key

In our dbms class, these were the four properties of a primary key discussed for Oracle. Unique Not NULL Fully functional dependency Indexed I understand all the properties except the 3rd one ...
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345 views

How SQLite index ID (or line number)

SQLite is based on a flatfile, and store virtual tables in a flatfile (I think based on offset, correct me if I'm wrong). But how it index the Primary Key (ID), which I think is identical to line ...
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2answers
76 views

Update datatype of primary key without deleting the table-SQL Server [closed]

I have created a table State which my other table, Addresses references. CREATE TABLE State ( StateId varchar(20) PRIMARY KEY NOT NULL, Text varchar(40) NOT NULL ) I want to change its ...
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3answers
72 views

Can i have one foreign key to both parent and it's childs in postgresql?

I want to have a foreign key to reference table and it's children. Here's how I tried and failed: CREATE TABLE parent ( id serial, CONSTRAINT parent_pk PRIMARY KEY(id) ); CREATE TABLE child ( ...
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1answer
37 views

Postgres table contains 1 column, and that column is PK. How to insert new record?

In my application, I have an abstract base class, and 2 derived classes. The number of derived classed will probably not increase. If it does, it won't be more than a few. The class structure looks ...
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1answer
57 views

How to include in the result of a `SELECT … GROUP BY …` all the other columns that are functionally dependent on the grouping ones?

I'll base this question on a toy example. Let this be table A: A ------------------------- U | V | W | X | Y | Z ------------------------- a | b | c | 1 | 6 | 8.3 a | b | c | 1 | 4 | ...
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123 views

Primary key for link/junction table with time-dependent data

I want to link two tables in such a way that for any given time period the relationship is one-to-one, but over time the relationship can change. As an minimal example, suppose I want to list the ...
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1answer
323 views

How to set up multiple fields as primary key in MySQL?

I have a table with fields EmployeeID blahblah blahblah2 ..... RecordMonth RecodrdYear so each employee should only have a matching entry for a month, year, Emp#. How do I set up a table. ...
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1answer
146 views

Implementing foreign keys on generalized data model

Suppose the ASCII tree below is a UML generalized concept model. To represent these entities/classes in UML, lets assume [mammal] a super class, and the level 1 classes, [wild] and [domestic] are sub ...
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2answers
1k views

Use timestamp(or datetime) as part of primary key (or part of clustered index)

I use following query frequently: SELECT * FROM table WHERE Timestamp > [SomeTime] AND Timestamp < [SomeOtherTime] and publish = 1 and type = 2 order by Timestamp I would like to optimize ...
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1answer
1k views

Changing primary key from varchar to int

I have a user table where I am use varchar as primary key. Now from a different place I got the performance tip that int is better than varchar for primary key. So I would like to change my primary ...
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1answer
1k views

Candidate key = Key = Minimal Superkey?

I got a little confused by all these keys. As I understand A key of a relational schema = The minimal subset of a superkey that is still a key = A candidate key Is this correct or not?
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3answers
80 views

Autoincrement Primary Key For Constants

We are having an issue that is probably due to some poor design choice or lack of understanding of how to use primary keys. We have a simple constants table CREATE TABLE IF NOT EXISTS `constants` ( ...
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2answers
86 views

VARCHAR primary key - MySQL

Currently, I have a categories table with 2 columns - category VARCHAR(50) NOT NULL PRIMARY KEY and parent VARCHAR(50). The parent column is a foreign key (FK) to the category column. This seems like ...
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109 views

Composite Primary Key column order

How would you do the ordering of the PK columns in this case (Oracle 11gR2 Standard Edition): I have a database where I offer the same application to many users. I want to be perfectly sure that all ...
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1answer
154 views

Relational database primary key requirements

I am trying to put together an ER Diagram to design a fairly simple asset tag tracking/inventory management system for our servers/switches/UPS/etc. The top-level entity corresponds to the business ...
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1answer
24 views

Which of tables key to reference?

MySQL. There is a table users with autoincrement primary key id. There is also a table employees (every employee is a user but not vice versa). The employees primary key is userid. The field userid ...
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1answer
362 views

MySQL non-sequential primary key of certain length

what's the best way to create a non-sequential primary key of a certain length in MySQL? I'm looking to use the primary key as a 'Pin' number which real actual human people can use to refer to the ...
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1answer
36 views

Database design: Which will perform better, auto incremented column or a composite key for appointments

The schema of table is : appointment(date,time,patientID,...) pateint(patientID,PName,age,...) PS: two or more patient can came at the same time . The number of appointments per day up to 500 . ...
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2answers
227 views

Msg 2627 Violation of PRIMARY KEY constraint

trying to make a database for teams in a tv show here. but when I try and insert data into tblShowteam the following error made its appearance. Msg 2627, Level 14, State 1, Line 2 Violation of ...
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525 views

postgresql bigserial or sequence using jpa

I'm a java developer working with jpa, before to define the indexes in my entities i would like to known which one is faster o better to use?.
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1answer
58 views

Can a complex primary key made up of 4 fields have only one of this fields set to AUTO INCREMENT?

I have a complex primary key, I wonder if what I write in the title is possible: I have a look up table with 4 fields (they should compose the primary key of the table): 1) an INT column; 2) ...
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1answer
86 views

Table design for departments with duplicate department numbers

How should I define a database table for my company's departments where we have a set of duplicate department numbers used by an upper management tier. dept_id dept_name manager_id ...
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1answer
77 views

How to arrange rows selected in MYSQL query?

I'm fetching data from a table "TABLE_A", it's having Primary Key as "PK_ONE" (which is unsigned INT) . I'm fetching data from "TABLE_A" with where clause on PK_ONE ; Ex: SELECT PK_ONE from TABLE_A ...
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1answer
328 views

Postgresql table with one integer column, sorted index, with duplicate primary key

I want to have a table in PostgreSQL with these properties: One column with an integer Allow duplicates in this column. Duplicates will be rare. Duplicates have no meaning logically and will be ...
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1answer
41 views

Modify legacy table schemas that have no primary key

I've been tasked with updating our database (SQL Server 2008) so that every table in it has a proper primary key defined. Due to various reasons over the years we have somehow built up some legacy ...
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1answer
304 views

Retrieving all PK and FK

I have a big database that I need to extract all primary keys and foreign keys from each table. I have pgAdmin III. Is there a way to do this automatically and not go over each table manually?
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How can primary keys in a Netezza table be indexed?

What is the best way to index a Netezza fact table with lots of primary keys. For now, let's suppose we have 10 primary keys. This table is mainly used to store meta data about our database. ...
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1answer
172 views

Impact of miss-ordered fields in a composite, clustered primary key?

I have tables where the primary key is something like this: -StoreID -BusinessDate Typically, there is one row for every store (~100) for every single day. One row for each store is inserted on a ...
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1answer
50 views

Prevent Primary Key increment when an INSERT statement fail in PostgreSQL

I have a simple table in my PostgreSQL database like this: CREATE TABLE person_type ( id serial NOT NULL, name character(55) NOT NULL, CONSTRAINT person_type_pkey PRIMARY KEY (id), CONSTRAINT ...
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27 views

Using partitioned table, and dealing with auto_increment PK

I have a big table (>100 million rows) that tracks user's activities. It has an ID, which is PK and has auto_increment property. This is the only unique key. Table also has userid and datetime column. ...
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21 views

MySQL on Server side PRIMARY KEY taking automatically random Id

I have problem in my database which i have uploaded in Database Version libmysql 5.1.73 In that i got problem like one PRIMARY_KEY field incrementing random values. inserted id's like 1, 2, 35, 67, ...