Add DB concepts section

[vo-eric]

Adds DB concepts section

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Important

Adds detailed explanations of basic and advanced database concepts to backend/database/README.md.

• Basic Concepts:
  • Defines a database as an electronically stored collection of data.
  • Explains columns, rows, and tables as structural elements of a database.
  • Describes a primary key as a unique identifier for table rows.
  • Differentiates between SQL, NoSQL, and Graph databases.
  • Defines data persistence and its importance.
  • Describes a data model as a structured way to organize and access data.
  • Defines ORM as a tool for interacting with databases through code objects.
• Advanced Concepts:
  • Explains 3rd Normal Form (3NF) for minimizing data redundancy.
  • Describes one-to-one, one-to-many, and many-to-many relationships in databases.

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[ellipsis-dev]

Caution

Changes requested ❌

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1. backend/database/README.md:18

• Draft comment:
  Consider using 'object-relational mapping (ORM)' instead of 'object-relational map' for clarity.
• Reason this comment was not posted:
  Decided after close inspection that this draft comment was likely wrong and/or not actionable: usefulness confidence = 10% vs. threshold = 50% While "object-relational mapping" is indeed the more common and technically correct term, this is a minor terminology issue in documentation. The current wording is still understandable and the acronym ORM is already introduced correctly. The meaning is clear either way. The suggested change would make the terminology more precise and consistent with industry standards. Documentation accuracy can be important for learning. However, this is an extremely minor correction that doesn't affect understanding or functionality. The current wording is still correct enough for a basic Q&A document. Delete the comment as it's too minor of a terminology suggestion to warrant a PR comment.

2. backend/database/README.md:16

• Draft comment:
  Typo: 'strutured' should be 'structured' in the description for the data model.
• Reason this comment was not posted:
  Decided after close inspection that this draft comment was likely wrong and/or not actionable: usefulness confidence = 20% vs. threshold = 50% While this is technically correct and about changed code, spelling fixes in documentation are very minor. The meaning is still clear despite the typo. This feels like the kind of nitpicky comment that creates noise without adding much value. Documentation typos don't affect functionality. The typo could confuse readers or make the documentation look unprofessional. Clear communication is important in technical documentation. While clear documentation is good, this minor typo doesn't significantly impact readability or understanding. The automated review should focus on more substantial issues. This comment should be removed as it's too minor and doesn't warrant interrupting the PR review process.

3. backend/database/README.md:25

• Draft comment:
  There seems to be an extra fragment ('In one to one.') at the beginning of the explanation of relationships. Consider removing or rephrasing it for clarity.
• Reason this comment was not posted:
  Decided after close inspection that this draft comment was likely wrong and/or not actionable: usefulness confidence = 10% vs. threshold = 50% The comment is technically correct - there is a redundant phrase that makes the text less clear. However, this is a documentation file with simple explanations, and the meaning is still clear despite the minor grammatical issue. The comment is about a very minor text issue that doesn't affect understanding or functionality. The text could be confusing to some readers, and clear documentation is important. Maybe we're undervaluing the importance of precise technical writing. While clear writing is important, this is a minor stylistic issue in an internal README file. The meaning is still clear, and this type of minor editorial feedback creates noise in code reviews. The comment should be deleted as it addresses a very minor grammatical issue that doesn't significantly impact the understanding of the content.

4. backend/database/README.md:29

• Draft comment:
  The line 'What is a database:' under the RESOURCES section appears out of place. Please confirm if this is intended or if it should be removed.
• Reason this comment was not posted:
  Comment was not on a location in the diff, so it can't be submitted as a review comment.

Workflow ID: wflow_2ucv8N7lCyS2yvX7

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[ellipsis-dev]

Typo: Replace 'strutured' with 'structured'.

Suggested change

	A strutured way of organizing data and defining how it is stored and accessed
	A structured way of organizing data and defining how it is stored and accessed

[ellipsis-dev]

Rephrase the relationship explanation for clarity; remove the redundant fragment 'In one to one.'

Suggested change

	one to one, one to many, and many to many. In one to one. In a one to one relationship, one row in a table is linked to a row in another. In a one to many relationship, one row in a table is linked to many rows in another. Finally, a many to many relationship has multiple rows in one table connecting to many rows in another table.
	one to one, one to many, and many to many. In a one to one relationship, one row in a table is linked to a row in another. In a one to many relationship, one row in a table is linked to many rows in another. Finally, a many to many relationship has multiple rows in one table connecting to many rows in another table.