Suggest an editImprove this articleRefine the answer for “What is a primary key (PRIMARY KEY)?”. Your changes go to moderation before they’re published.Approval requiredContentWhat you’re changing🇺🇸EN🇺🇦UAPreviewTitle (EN)Short answer (EN)A primary key (PRIMARY KEY) is a field or combination of fields in a table that uniquely identifies every record: its value never repeats in any other record of the table, and the field can never be empty (`NULL`). **Key point:** it's what lets the database know exactly which record is which, and it's the primary key that lets tables be linked together - it's a "passport" for every record.Shown above the full answer for quick recall.Answer (EN)ImageA **primary key (PRIMARY KEY)** is a field or combination of fields in a table that **uniquely identifies every record**. ### The main points 1. **Uniqueness**: the primary key's value never repeats in any other record of the table. 2. **Mandatory**: a field that's a primary key can never be empty (`NULL`). 3. **Identifying records**: it's how the database knows exactly which record is which. 4. **Example**: in an `Employees` table, the `ID` field could be the primary key, where `1` is the first employee, `2` the second, and so on. Put simply, **a primary key is a "passport" for every record in a table**, making it unique and allowing tables to be linked together.For the reviewerNote to the moderator (optional)Visible only to the moderator. Helps review go faster.