SQL Dialects Comparison: MySQL vs PostgreSQL vs SQL Server vs Oracle vs SQLite

Meta Description: Compare major SQL dialects: MySQL, PostgreSQL, SQL Server, Oracle, and SQLite. Learn syntax differences, feature comparisons, and choose the right database for your project.

Choosing the right SQL database is a critical architectural decision. Each major SQL dialect has distinct strengths, syntax variations, and optimal use cases. This comprehensive comparison helps you understand the differences and make informed decisions for your projects.

Quick Comparison Overview

Feature	MySQL	PostgreSQL	SQL Server	Oracle	SQLite
License	GPL/Commercial	MIT	Proprietary	Proprietary	Public Domain
ACID Compliant	Yes	Yes	Yes	Yes	Yes
Best For	Web apps	Complex apps	Enterprise	Enterprise	Mobile/Embedded
Scalability	High	High	Very High	Very High	Low
JSON Support	Yes	Yes	Yes	Yes	Yes

Pagination Syntax Comparison

Pagination is one of the most common operations with significant dialect differences.

MySQL Pagination

SELECT id, name, email
FROM users
WHERE status = 'active'
ORDER BY created_at DESC
LIMIT 10 OFFSET 20;

MySQL uses LIMIT ... OFFSET syntax, which is intuitive and widely adopted.

PostgreSQL Pagination

SELECT id, name, email
FROM users
WHERE status = 'active'
ORDER BY created_at DESC
LIMIT 10 OFFSET 20;

PostgreSQL shares the same LIMIT ... OFFSET syntax as MySQL but also supports FETCH FIRST:

SELECT id, name, email
FROM users
WHERE status = 'active'
ORDER BY created_at DESC
FETCH FIRST 10 ROWS ONLY;

SQL Server Pagination

SELECT id, name, email
FROM users
WHERE status = 'active'
ORDER BY created_at DESC
OFFSET 20 ROWS
FETCH NEXT 10 ROWS ONLY;

SQL Server also supports TOP for simple limits:

SELECT TOP 10 id, name, email
FROM users
WHERE status = 'active'
ORDER BY created_at DESC;

Oracle Pagination

SELECT id, name, email
FROM (
    SELECT
        u.*,
        ROWNUM as rn
    FROM (
        SELECT id, name, email
        FROM users
        WHERE status = 'active'
        ORDER BY created_at DESC
    ) u
    WHERE ROWNUM <= 30
)
WHERE rn > 20;

Oracle 12c+ supports simpler syntax:

SELECT id, name, email
FROM users
WHERE status = 'active'
ORDER BY created_at DESC
OFFSET 20 ROWS FETCH NEXT 10 ROWS ONLY;

SQLite Pagination

SELECT id, name, email
FROM users
WHERE status = 'active'
ORDER BY created_at DESC
LIMIT 10 OFFSET 20;

SQLite uses the same LIMIT ... OFFSET syntax as MySQL and PostgreSQL.

Auto-Increment Syntax Comparison

Auto-increment columns are essential for primary keys, but syntax varies significantly.

MySQL Auto-Increment

CREATE TABLE users (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(100),
    email VARCHAR(255)
);

PostgreSQL Auto-Increment

CREATE TABLE users (
    id SERIAL PRIMARY KEY,
    name VARCHAR(100),
    email VARCHAR(255)
);

Or using identity columns (PostgreSQL 10+):

CREATE TABLE users (
    id INT GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
    name VARCHAR(100),
    email VARCHAR(255)
);

SQL Server Auto-Increment

CREATE TABLE users (
    id INT IDENTITY(1,1) PRIMARY KEY,
    name VARCHAR(100),
    email VARCHAR(255)
);

Oracle Auto-Increment

Oracle 12c+ supports identity columns:

CREATE TABLE users (
    id NUMBER GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
    name VARCHAR2(100),
    email VARCHAR2(255)
);

SQLite Auto-Increment

CREATE TABLE users (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    name TEXT,
    email TEXT
);

String Functions Comparison

String manipulation functions vary significantly across dialects.

String Concatenation

Database	Syntax	Example
MySQL	`CONCAT()`	`CONCAT(first_name, ' ', last_name)`
PostgreSQL	`
SQL Server	`+`	`first_name + ' ' + last_name`
Oracle	`
SQLite	`

String Length

Database	Syntax
MySQL	`LENGTH(string)` or `CHAR_LENGTH(string)`
PostgreSQL	`LENGTH(string)` or `CHAR_LENGTH(string)`
SQL Server	`LEN(string)`
Oracle	`LENGTH(string)`
SQLite	`LENGTH(string)`

Substring

Database	Syntax
MySQL	`SUBSTRING(string, start, length)` or `SUBSTR()`
PostgreSQL	`SUBSTRING(string, start, length)` or `SUBSTR()`
SQL Server	`SUBSTRING(string, start, length)`
Oracle	`SUBSTR(string, start, length)`
SQLite	`SUBSTR(string, start, length)`

Date/Time Functions Comparison

Date handling shows the most variation among SQL dialects.

Current Date/Time

Database	Current Date	Current Time	Current Timestamp
MySQL	`CURDATE()`	`CURTIME()`	`NOW()`
PostgreSQL	`CURRENT_DATE`	`CURRENT_TIME`	`CURRENT_TIMESTAMP`
SQL Server	`CAST(GETDATE() AS DATE)`	`CAST(GETDATE() AS TIME)`	`GETDATE()`
Oracle	`SYSDATE`	`SYSTIMESTAMP`	`SYSTIMESTAMP`
SQLite	`DATE('now')`	`TIME('now')`	`DATETIME('now')`

Date Arithmetic

MySQL:

SELECT DATE_ADD(created_at, INTERVAL 7 DAY) FROM users;
SELECT DATEDIFF(NOW(), created_at) FROM users;

PostgreSQL:

SELECT created_at + INTERVAL '7 days' FROM users;
SELECT NOW() - created_at FROM users;

SQL Server:

SELECT DATEADD(day, 7, created_at) FROM users;
SELECT DATEDIFF(day, created_at, GETDATE()) FROM users;

Oracle:

SELECT created_at + 7 FROM users;
SELECT SYSDATE - created_at FROM users;

SQLite:

SELECT DATE(created_at, '+7 days') FROM users;
SELECT JULIANDAY('now') - JULIANDAY(created_at) FROM users;

Conditional Expressions Comparison

CASE Statement (Universal)

SELECT
    name,
    CASE
        WHEN score >= 90 THEN 'A'
        WHEN score >= 80 THEN 'B'
        WHEN score >= 70 THEN 'C'
        ELSE 'F'
    END as grade
FROM students;

IF/IFF Functions

Database	Syntax
MySQL	`IF(condition, true_value, false_value)`
PostgreSQL	`CASE WHEN condition THEN true_value ELSE false_value END`
SQL Server	`IIF(condition, true_value, false_value)`
Oracle	`CASE WHEN condition THEN true_value ELSE false_value END`
SQLite	`IIF(condition, true_value, false_value)`

NULL Handling

Database	COALESCE	NULLIF	IFNULL/NVL
MySQL	`COALESCE()`	`NULLIF()`	`IFNULL()`
PostgreSQL	`COALESCE()`	`NULLIF()`	`COALESCE()`
SQL Server	`COALESCE()`	`NULLIF()`	`ISNULL()`
Oracle	`COALESCE()`	`NULLIF()`	`NVL()`
SQLite	`COALESCE()`	`NULLIF()`	`IFNULL()`

JSON Support Comparison

Modern applications increasingly use JSON. Here's how each dialect handles it.

MySQL JSON Functions

SELECT JSON_EXTRACT(data, '$.name') FROM users;
SELECT JSON_UNQUOTE(JSON_EXTRACT(data, '$.email')) FROM users;

PostgreSQL JSON Functions

SELECT data->>'name' FROM users;
SELECT data->'email' FROM users;

SQL Server JSON Functions

SELECT JSON_VALUE(data, '$.name') FROM users;
SELECT JSON_QUERY(data, '$.address') FROM users;

Oracle JSON Functions

SELECT JSON_VALUE(data, '$.name') FROM users;
SELECT JSON_QUERY(data, '$.address') FROM users;

SQLite JSON Functions

SELECT JSON_EXTRACT(data, '$.name') FROM users;
SELECT JSON_EXTRACT(data, '$.email') FROM users;

Identifier Quoting Comparison

When using reserved words or special characters as identifiers, quoting is required.

Database	Quote Style	Example
MySQL	Backticks	`order`
PostgreSQL	Double quotes	`"order"`
SQL Server	Square brackets	`[order]`
Oracle	Double quotes	`"order"`
SQLite	Double quotes	`"order"`

When to Choose Each Database

Choose MySQL When

Building web applications with high read traffic
Need simple, fast deployment
Using PHP, Python, or Node.js stacks
Budget is a primary concern
Need strong community support

Choose PostgreSQL When

Need advanced features (full-text search, JSON, arrays)
Building complex applications with stored procedures
Require strict SQL compliance
Need extensibility (custom types, functions)
Working with geospatial data (PostGIS)

Choose SQL Server When

Working in Microsoft ecosystem
Need enterprise-grade security and compliance
Building data warehouses
Require advanced analytics (SSAS, SSRS)
Need tight integration with Azure

Choose Oracle When

Building mission-critical enterprise applications
Need advanced high availability features
Require partitioning and parallel processing
Working with large-scale OLTP systems
Budget allows for enterprise licensing

Choose SQLite When

Building mobile or desktop applications
Need embedded database with zero configuration
Building prototypes or MVPs
Working with local data storage
Need zero-administration database

Conclusion

Understanding SQL dialect differences helps you write portable queries and choose the right database for your project. While SQL standards exist, each database implements features differently.

Use our free SQL Formatter to format queries for your specific dialect, ensuring consistent, readable SQL code regardless of which database you choose.