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Questions tagged [rdbms]

A relational database management system (RDBMS) is a database management system (DBMS) in which data is stored in tables and the relationships among the data are also stored in tables.

A relational database management system (RDBMS) is a database management system () that is based on the relational model as introduced by E. F. Codd, of IBM's San Jose Research Laboratory. Many popular databases that are currently in use are based on the relational database model.

RDBMSs have become a predominant choice for the storage of information in new databases used for financial records, manufacturing and logistical information, personnel data, and much more. Relational databases have often replaced legacy hierarchical databases and network databases because they are easier to understand and use. However, relational databases have been challenged by object databases, which were introduced in an attempt to address the object-relational impedance mismatch in relational database, and XML databases.

History:
The development for the RDBMS model began at in 1974
The first commercially available RDBMS system was in 1979
The first RDBMS system for Mac OS was in 1984

References:

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Is this zero-downtime database migration plan viable?

I am pondering about performing a zero-downtime database migration and came up with minimum necessary steps. By "migration" I mean any change in the same database that is not backward-compatible such as renaming, splitting or dropping a…
raiks
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Postgres | Execute delete cte after insert cte

I have a table: CREATE TABLE product ( id bigint GENERATED ALWAYS AS IDENTITY PRIMARY KEY, from_id bigint NOT NULL, to_id bigint NOT NULL, comments text NOT NULL, data jsonb NOT NULL ); CREATE UNIQUE INDEX…
Shay Zambrovski
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How to keep RDBMS in sync with Hive through Nifi or sqoop in terms of updation of same record instead of creating a new one

Requirement: Need to fetch 1000s of tables from RDBMS (SQL Server) and push it in Hive for running analytics and generating reports in near real time. I am using Nifi to read data from RDBMS tables and pushing to hive tables as external…
Roobal Jindal
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nosql vs rdbms hardware specs

Generally its believed that RDBMS scales better vertically while nosql are designed specifically to scale horizontally. What kind of databases would be better fit for this kind of…
Gary Lindahl
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How to write query for this given result?

Table "question": q_id s_id question 8 1 9 1 10 1 Table "result": id q_id s_id answer 1 8 1 yes 2 9 1 no 3 10 1 yes 4 8 1 no 5 9 1 yes 6 10 1 yes I want the result to look like this how can I do this can anyone…
Gourav Srivastava
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How to model this Category and Product relationship in RDBMS?

I am trying to design a database for nested categories of products, e.g. "men/shoes/sandals", "women/shoes", or "men/jeans". I can model it with two entities Category and Product. The "subcategory" Category-to-Category relationship is many-to-many.…
Michael
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Is the relationship between the Department entity and the Instructor entity in Microsoft's Contoso University model wrong?

Following this tutorial on Microsoft's documentation site... The relationship between the Instructor table and Department table shows a 0..1 on the Instructor and a * on the Department. If this statement is true: A department may or may not have an…
bigSloppy
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DB Schema design, table with many columns

I'm designing a schema for a learner management system. I currently have LearnerDetails table which stores below categories of information. - login user account details - contact details and home address - learner's residency related information…
Eranga Dissanayaka
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How to select only rows having max value, but maintaining date timeline

I have this table: id price sold_at 4 30 2022-01-04 3 15 2022-01-03 2 30 2022-01-02 1 30 2022-01-01 And I want to aggregate the price column, but only the consecutive values in the solt_at timeline. I want to select the latest…
Soichi Takamura
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I'm facing issue building MySQL query. I need to get value in end date column from start column

I'm facing issue regarding getting end_date of previous designation based on the start_date of new designation. Designation 1: House job officer Designation 2: Medical officer Designation 3: Doctor If employee is promoted to next designation…
abacus-A
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How to Select a specific name from a group in a table?

This is my table: The table Now I grouped classes and wanted to select the first_name from each group(class) with the highest marks. But in class 7 group, I am getting 'edward' instead of 'tony' even though tony has higher marks. how should I order…
yashvanth Gumparthi
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SQL Query required ot get records count on hourly basis

I am trying to get records from 29th April,2022 on hourly basis from Oracle DB, however with the below query I am getting records count older than 29th April as well(all previous records count as well). Can you help fine tune the query? SELECT…
Ashok
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Version control of business objects

Is there a recognised pattern that addresses being able to "version" business objects in a web application, persisted in a RDBMS? As an example if an audit log from a web application read thus: 2011-08-20 14:05:00 User A added changed setting "A" of…
Wendell Urth
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Does SQL write lock makes other transactions re-evaluate all queries in the tranasction

I'm pretty new to database locking and had a basic question. My understanding is that any UPDATE statement locks the row in the table and hence, no other transaction can read/write that row. If so, consider a scenario: Initial table: user_id = 1,…
Zeeshan Shamsuddeen
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Optimize LIMIT the number of rows to be SELECT in SQL

Consider a table Test having 1000 rows Test Table id name desc 1 Adi test1 2 Sam test2 3 Kal test3 . . 1000 Jil test1000 If I need to fetch, say suppose 100 rows(i.e. a small subset) only, then I am using the LIMIT clause in my…
Aditya Rewari
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