Engineering English
Primary Key
Software Engineering · Last updated: July 30, 2026 · How this entry was written
Definition: A primary key is a unique identifier for each record in a relational database table. It ensures that no two rows have the same value in the key column(s) and that each record can be uniquely accessed.
Example in context
“We defined the employee ID as the primary key in the employees table to guarantee that each employee can be uniquely identified by that column.”
“Çalışan tablosunda, çalışan kimliğini birincil anahtar olarak tanımladık, böylece her çalışanın o sütun tarafından benzersiz şekilde tanımlanmasını garanti altına aldık.”
Where engineers use it
The primary key is defined when creating or altering a table in a database. Engineers rely on it for indexing, enforcing uniqueness, and enabling fast lookups by that column in queries and joins.
Synonyms: PK, primary index
Antonyms: foreign key
Practice: can you use “Primary Key” at work?
During a code review, you notice a table that lacks a primary key. Explain why this is problematic and suggest how to implement one to ensure data integrity and query efficiency.
Show a model answer
“Always use an auto-incrementing integer column as the primary key for best performance.”
“Primary Key” in 21 languages
| English | Primary Key |
|---|---|
| Turkish | Birincil Anahtar |
| French | Clé Primaire |
| German | Primärschlüssel |
| Spanish | Clave Primaria |
| Chinese | 主键 |
| Arabic | المفتاح الأساسي |
| Portuguese | Chave Primária |
| Russian | Первичный ключ |
| Japanese | 主キー |
| Italian | Chiave Primaria |
| Vietnamese | Khóa Chính |
| Hindi | प्राथमिक कुंजी |
| Thai | คีย์หลัก |
| Indonesian | Kunci Utama |
| Korean | 기본 키 |
| Bengali | প্রাথমিক কী |
| Dutch | Primaire Sleutel |
| Swedish | Primärnyckel |
| Finnish | Pääavain |
| Ukrainian | Первинний ключ |
Frequently asked questions
What does Primary Key mean in engineering?
A primary key is a unique identifier for each record in a relational database table. It ensures that no two rows have the same value in the key column(s) and that each record can be uniquely accessed. In Software Engineering, the term carries a usage-frequency rating of 10/10 in the Engineering English library.
How do you pronounce Primary Key?
Primary Key is pronounced /ˈpraɪməri kiː/ (IPA). The Engineering English app plays audio for the term and checks your pronunciation with speech recognition.
How is Primary Key used in a sentence?
Example from an engineering context: “We defined the employee ID as the primary key in the employees table to guarantee that each employee can be uniquely identified by that column.”
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