PostgreSQL to SQL Server Converter - Free Online Tool 2025

Migrating from PostgreSQL to SQL Server is a common requirement for organizations scaling up, integrating with Microsoft ecosystems, or standardizing data infrastructure. However, moving databases between these platforms can pose major challenges: distinct SQL dialects, data type incompatibilities, and procedural differences often result in failed migrations and extensive debugging. The need to refactor queries and scripts for SQL Server’s T-SQL syntax further complicates projects.

AI2sql eliminates the manual effort and reduces conversion errors by transforming PostgreSQL queries into production-ready SQL Server code—all from natural language prompts. In minutes, you can bridge PostgreSQL and SQL Server syntax without deep expertise or manual pain.

PostgreSQL to SQL Server Migration Overview

This cross-platform migration scenario is popular for:

  • Integrating with Microsoft analytics and reporting tools

  • Unifying data sources for enterprise applications

  • Modernizing legacy PostgreSQL workloads

  • Leveraging SQL Server security, HA, or advanced features

Yet, the process isn’t seamless. Syntax, data types, and procedural logic need careful handling to ensure business continuity and data quality.

Key Syntax Differences: PostgreSQL vs SQL Server

While both databases are SQL-based, PostgreSQL and SQL Server differ significantly in syntax and supported features. Key areas to address during migration:

  • String concatenation: || (PostgreSQL) vs + (SQL Server)

  • Identifier quoting: "..." (PostgreSQL) vs [...] or '...' (SQL Server)

  • Auto-increment: SERIAL (PostgreSQL) vs IDENTITY (SQL Server)

  • Function names and usage: NOW() vs GETDATE(), ILIKE not present in SQL Server

  • LIMIT/OFFSET vs TOP and OFFSET FETCH

OperationPostgreSQLSQL Server
String ConcatenationSELECT 'A' || 'B';SELECT 'A' + 'B';
Current Date/TimeSELECT NOW();SELECT GETDATE();
Limit RowsSELECT * FROM t LIMIT 10;SELECT TOP 10 * FROM t;
Auto Incrementid SERIAL PRIMARY KEYid INT IDENTITY(1,1) PRIMARY KEY
Case Insensitive LIKEWHERE name ILIKE 'foo%'WHERE LOWER(name) LIKE 'foo%'

Data Type Mapping Guide

Translating data types ensures data integrity in SQL Server. Key mappings:

  • INTEGER / SERIAL (PostgreSQL): INT / IDENTITY (SQL Server)

  • TEXT / VARCHAR(n): NVARCHAR(n) or VARCHAR(n)

  • BOOLEAN: BIT

  • TIMESTAMP WITH TIME ZONE: DATETIMEOFFSET

  • BYTEA: VARBINARY(MAX)

PostgreSQLSQL Server
INTEGERINT
BIGSERIALBIGINT IDENTITY(1,1)
TEXTNVARCHAR(MAX)
BOOLEANBIT
BYTEAVARBINARY(MAX)
TIMESTAMPDATETIME2

Common Conversion Challenges

  • Function Differences: Common PostgreSQL functions need rewriting (e.g., string_agg → STRING_AGG)

  • Procedural Logic: PL/pgSQL constructs differ from T-SQL in syntax and control flow

  • Array Types: SQL Server lacks native array support, requiring normalization

  • Identifier and Case Sensitivity: SQL Server is case-insensitive by default; PostgreSQL can be case-sensitive

  • Error Handling: Exception blocks and error codes conversion

Step-by-Step Migration Process

  1. Assess database objects: Review tables, views, procedures, triggers, and functions for incompatibilities.

  2. Map data types and constraints: Update or convert to SQL Server-compatible definitions.

  3. Rewrite SQL queries: Adjust syntax, replace functions, and use SQL Server idioms.

  4. Move and validate data: Use ETL tools or scripts, ensuring encoding and data conformity.

  5. Test and optimize: Compare outputs, monitor performance, and tune as needed for SQL Server workloads.

AI2sql: Generate SQL Server Queries from Natural Language

With AI2sql platform, you eliminate tedious refactoring. Enter your intent or existing PostgreSQL query in plain English; get an instant, production-ready SQL Server query complete with migrated syntax, data types, and error-free formatting. No deep syntax knowledge or manual conversion needed.

Practical Conversion Examples

ScenarioPostgreSQLSQL Server
1. String ConcatenationSELECT first_name || ' ' || last_name FROM users;SELECT first_name + ' ' + last_name FROM users;
2. Limit RowsSELECT * FROM orders LIMIT 5;SELECT TOP 5 * FROM orders;
3. Date/Time RetrievalSELECT NOW();SELECT GETDATE();
4. Auto-increment Column
5. Case-insensitive SearchSELECT * FROM emp WHERE name ILIKE '%dev%';SELECT * FROM emp WHERE LOWER(name) LIKE '%dev%';

Troubleshooting Common Conversion Errors

  • Data type mismatches: Ensure every column’s type exists in SQL Server; BIT for BOOLEAN, VARBINARY for BYTEA.

  • Illegal keyword/identifier usage: Enclose reserved words in [brackets] or change object names.

  • Syntax errors in joins: Check JOIN and ON clause; SQL Server enforces stricter standards than PostgreSQL.

  • Missing default values/constraints: Explicitly specify in table definitions where needed.

  • Unsupported array/JSON operators: Convert arrays to normalized tables or use SQL Server JSON functions.

Performance Tips for SQL Server Optimization

  • Leverage clustered/non-clustered indexes for query speed

  • Convert CTEs and window functions thoughtfully, as execution plans may differ

  • Set proper collation and encoding (Unicode support via NVARCHAR)

  • Refactor subqueries or lateral joins to compatible constructs

  • Regularly update statistics and consider partitioning for large datasets

Why Use AI2sql for Your PostgreSQL to SQL Server Migration?

  • No manual query rewriting: Convert complex queries with a single prompt

  • Supports all databases: 15+ SQL dialects covered

  • Error-free conversion: Automated syntax mapping and type translation

  • Enterprise-grade accuracy: Used by 50,000+ developers globally

  • Instant results: Get production-ready SQL Server code in seconds

Skip manual conversion - Generate SQL Server queries instantly with AI2sql using natural language.

Further Reading and Tools

Conclusion: Simplify Your PostgreSQL to SQL Server Migration

Traditional PostgreSQL to SQL Server migration demands expensive expertise and error-prone manual conversions. AI2sql automates every step: from syntax and data type translation to best-practice query generation. Eliminate frustration, reduce project timelines, and deploy with confidence—no matter your SQL knowledge level. Unlock the power of instant, reliable SQL Server SQL from plain English and accelerate your cross-platform migration journey.

Try AI2sql Free - Generate SQL Server Queries from Plain English

Generate Your SQL Now

Share this

TOOLS

Build Your Own AI Agent Team in 15 Min — Free OpenClaw Guide

Feb 5, 2026

TOOLS

OpenClaw AI Assistant: Local 24/7 Automation Guide 2026

Feb 4, 2026

TOOLS

SQL WITH Clause (CTE): Complete Guide with Examples

Jan 14, 2026

TOOLS

MySQL to PostgreSQL Migration: Complete 2026 Guide with Syntax Conversion

Jan 14, 2026

TOOLS

SQL vs Excel: When Should You Make the Switch? [2026]

Jan 14, 2026

Copyright © AI2sql 2026

Cross Regions Technology

13553 Atlantic Blvd, Suite 201

FL 32225

support@ai2sql.io

Company