---
title: "Difference between IDENTITY vs SEQUENCE."  
description: "Difference between IDENTITY vs SEQUENCE."  
author: "Anubhav Sharma"  
published: 2026-05-07  
updated: 2026-05-07  
canonical: https://www.mindstick.com/interview/34504/difference-between-identity-vs-sequence  
category: "database"  
tags: ["database", "sql server"]  
reading_time: 4 minutes  

---

# Difference between IDENTITY vs SEQUENCE.

`IDENTITY` and `SEQUENCE` are both used to generate numeric values automatically in SQL databases, but they work differently and are suited for different scenarios.

## Quick Comparison

| Feature | IDENTITY | SEQUENCE |
| --- | --- | --- |
| Tied to a table column | Yes | No |
| Reusable across tables | No | Yes |
| Generates values automatically on insert | Yes | Usually via `NEXT VALUE FOR` / `nextval()` |
| Custom control over generation | Limited | More flexible |
| Can generate numbers before insert | No | Yes |
| Reset/restart support | Limited | Easier |
| Standard SQL feature | Vendor-specific origins | ANSI SQL standard |

## 1. IDENTITY

An `IDENTITY` column auto-generates values when rows are inserted.

Example in Microsoft SQL Server:

```plaintext
CREATE TABLE Employees (
    EmployeeID INT IDENTITY(1,1),
    Name VARCHAR(100)
);
```

Here:

- First `1` = start value
- Second `1` = increment

Inserted rows automatically get:

```plaintext
1, 2, 3, 4...
```

## Characteristics

- Bound directly to one table column
- Mostly used for primary keys
- Simpler setup
- Less flexible

## Common Databases Supporting IDENTITY

- Microsoft SQL Server
- PostgreSQL (`GENERATED AS IDENTITY`)
- Oracle Database (12c+)
- IBM Db2

## 2. SEQUENCE

A `SEQUENCE` is an independent database object that generates numbers.

Example in Oracle Database or PostgreSQL:

```plaintext
CREATE SEQUENCE emp_seq
START WITH 1
INCREMENT BY 1;
```

Use it:

```plaintext
INSERT INTO Employees(EmployeeID, Name)
VALUES(nextval('emp_seq'), 'John');
```

## When to Use Which?

## Use IDENTITY when:

- Simple primary key generation
- One table only
- Minimal configuration needed
- Standard CRUD applications

## Use SEQUENCE when:

- Multiple tables share numbering
- Need custom numbering logic
- Need numbers before insert
- High scalability/concurrency
- Enterprise workflows

## Interview-Friendly Summary

> IDENTITY is a table-bound auto-increment column, while SEQUENCE is an independent object that generates reusable numeric values with greater flexibility and control.

## Answers

### Answer by Anubhav Sharma

`IDENTITY` and `SEQUENCE` are both used to generate numeric values automatically in SQL databases, but they work differently and are suited for different scenarios.

## Quick Comparison

| Feature | IDENTITY | SEQUENCE |
| --- | --- | --- |
| Tied to a table column | Yes | No |
| Reusable across tables | No | Yes |
| Generates values automatically on insert | Yes | Usually via `NEXT VALUE FOR` / `nextval()` |
| Custom control over generation | Limited | More flexible |
| Can generate numbers before insert | No | Yes |
| Reset/restart support | Limited | Easier |
| Standard SQL feature | Vendor-specific origins | ANSI SQL standard |

## 1. IDENTITY

An `IDENTITY` column auto-generates values when rows are inserted.

Example in Microsoft SQL Server:

```plaintext
CREATE TABLE Employees (
    EmployeeID INT IDENTITY(1,1),
    Name VARCHAR(100)
);
```

Here:

- First `1` = start value
- Second `1` = increment

Inserted rows automatically get:

```plaintext
1, 2, 3, 4...
```

## Characteristics

- Bound directly to one table column
- Mostly used for primary keys
- Simpler setup
- Less flexible

## Common Databases Supporting IDENTITY

- Microsoft SQL Server
- PostgreSQL (`GENERATED AS IDENTITY`)
- Oracle Database (12c+)
- IBM Db2

## 2. SEQUENCE

A `SEQUENCE` is an independent database object that generates numbers.

Example in Oracle Database or PostgreSQL:

```plaintext
CREATE SEQUENCE emp_seq
START WITH 1
INCREMENT BY 1;
```

Use it:

```plaintext
INSERT INTO Employees(EmployeeID, Name)
VALUES(nextval('emp_seq'), 'John');
```

## When to Use Which?

## Use IDENTITY when:

- Simple primary key generation
- One table only
- Minimal configuration needed
- Standard CRUD applications

## Use SEQUENCE when:

- Multiple tables share numbering
- Need custom numbering logic
- Need numbers before insert
- High scalability/concurrency
- Enterprise workflows

## Interview-Friendly Summary

> IDENTITY is a table-bound auto-increment column, while SEQUENCE is an independent object that generates reusable numeric values with greater flexibility and control.


---

Original Source: https://www.mindstick.com/interview/34504/difference-between-identity-vs-sequence

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