HyperTeamsWhat a database is
What you will learn How a database differs from a spreadsheet, how to read tables, rows, columns and keys, the shape of one line of SQL, and why "read-only account" keeps coming up.
Where a company's facts pile up
Orders, members, stock, payments. Records that grow daily live in a database. Nearly every number you see on a screen came out of one.
It is tables
The most common kind — a relational database — holds data in tables.
The orders table
| id | customer_id | ordered_at | amount | status |
|---|---|---|---|---|
| 1001 | 42 | 2026-08-01 | 128000 | paid |
| 1002 | 7 | 2026-08-01 | 34000 | refunded |
| Term | Meaning |
|---|---|
| Table | one table — usually one kind of fact |
| Row (record) | one line across — one event |
| Column (field) | one slot down — one attribute |
| Primary key (PK) | the value that names one row — id above |
| Foreign key (FK) | a value pointing at another table — customer_id above |
Foreign keys are what "relational" means. Instead of copying the customer's name into every order, you store the number and fetch the name from the customer table. So when a customer changes their name, you change one place.
graph TD
A["orders<br/>id · customer_id · amount"] -->|"joined by customer_id"| B["customers<br/>id · name · email"]How it differs from a spreadsheet
| Spreadsheet | Database | |
|---|---|---|
| Simultaneous edits | conflicts, copies breed | many people at once |
| Volume | struggles past a few hundred thousand rows | hundreds of millions |
| Rules | any value goes in | format, required, uniqueness enforced |
| Permissions | per file | per table, per column |
| History | who changed it? | can be recorded |
"final.xlsx / final_really.xlsx is breeding" is the signal to move. Once copies exist, nobody knows which one is the fact.
SQL — how you ask a database
A query looks like this. It is close enough to English that reading it is learnable.
| Piece | Meaning |
|---|---|
SELECT | what to show |
FROM | from which table |
WHERE | which rows to keep |
GROUP BY | what to group by |
Attach a database to an agent and it writes these for you (Attaching a database). Removing the need to know SQL is the point of that feature.
Reading and writing are different in kind
| Kind | SQL | Reversible |
|---|---|---|
| Read | SELECT | changes nothing |
| Insert | INSERT | delete it again |
| Update | UPDATE | the old value is gone |
| Delete | DELETE · DROP | not reversible |
UPDATE and DELETE apply to the whole table when the condition is
missing. That one-line difference is how every customer gets upgraded at once.
So you block it with the account
This is why the manual keeps saying "read-only account". Every database account has a defined set of things it may do.
Deciding by instruction and blocking by permission are different. Instructions can drift or be overridden by outside input; account permissions are enforced by the database — the database edition of Tools are permissions.
Kinds — the names are enough
| Kind | Example | Character |
|---|---|---|
| Relational | PostgreSQL · MySQL | tables and relations. The common case |
| File-based | SQLite | one file is the database |
| Document | MongoDB | stores JSON-like blobs |
| Vector | pgvector and others | finding things close in meaning — used by grounding |
The last row connects directly to AI. Sentences are stored as lists of numbers (embeddings) so you can retrieve "documents close in meaning".
Backups — check exactly this
The second line is the real one. Backups running and restores working are different facts, and the difference only shows on the day it matters.
Common misconceptions
"Our data is all in spreadsheets — can we not use AI?"
You can. But Phase 2 — data and system assessment asks "what lives where", and scattered spreadsheets make that step slow.
"If I attach a database to an agent, does our data leave?"
Query results feed into producing the answer. So you narrow what is reachable (account permissions) and hide values that must not leave with masking.
Check yourself
1. What does a foreign key do?
Answer
Points at a row in another table, so the same information is not copied everywhere and one edit is enough.
2. The most dangerous mistake with UPDATE?
Answer
Omitting the WHERE condition. It applies to the entire table and the old
values do not come back.
3. Why is a read-only account stronger than a tool setting?
Answer
Different enforcer. Instructions and settings can change; account permissions are enforced by the database itself.
The last chapter of this part → Accounts, passwords, API keys, permissions