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SQL Server to PostgreSQL Converter - Free Migration Tool 2025 | AI2sql
SQL Server to PostgreSQL Converter - Free Online Tool 2025
Migrating from SQL Server to PostgreSQL is a common challenge for enterprises pursuing open-source adoption, cloud modernization, or cost optimization. Despite both being powerful relational databases, converting SQL Server queries, schema, and data to work seamlessly on PostgreSQL is complex due to syntax differences, data type mismatches, and platform-specific functions. Manual rewrite is slow, error-prone, and risky for business-critical workloads.
AI2sql offers a smarter path. As an intelligent migration solution, it generates PostgreSQL-compliant SQL directly from natural language or existing SQL Server statements, eliminating tedious code reviews and translation errors. Whether you're modernizing legacy systems or scaling analytics in the cloud, AI2sql minimizes downtime and maximizes migration success for teams of any size.
SQL Server to PostgreSQL Migration Overview
Enterprises often migrate from SQL Server to PostgreSQL to leverage open-source flexibility, cloud compatibility, and lower licensing fees. Key migration steps include:
Schema conversion (tables, indexes, constraints)
Data type mapping
View, procedure, and function translation
Data transfer and integrity checks
Optimization and validation
Each stage presents unique conversion challenges, amplified in large or complex environments. AI2sql accelerates SQL code transformation for a robust, secure PostgreSQL migration.
Key Syntax Differences: SQL Server vs PostgreSQL
Operation | SQL Server Syntax | PostgreSQL Syntax |
---|---|---|
Select Top N Rows |
|
|
String Concatenation |
|
|
Auto-increment |
|
|
Get Current Date/Time |
|
|
Explicit Join |
|
|
IF Statement |
|
|
Data Type Mapping Guide
Data type compatibility is critical for accurate migrations. This guide summarizes common type conversions:
SQL Server | PostgreSQL |
---|---|
INT | INTEGER |
VARCHAR(n) | VARCHAR(n) |
NVARCHAR(n) | VARCHAR(n) |
DATETIME | TIMESTAMP |
BIT | BOOLEAN |
MONEY | NUMERIC |
UNIQUEIDENTIFIER | UUID |
Common Conversion Challenges
String operations: SQL Server’s
+
for concatenation vs PostgreSQL’s||
Auto-increment columns:
IDENTITY
is replaced bySERIAL
orGENERATED BY DEFAULT AS IDENTITY
Function differences: e.g.,
GETDATE()
becomesCURRENT_TIMESTAMP
Stored procedures: T-SQL syntax must be re-authored for PostgreSQL’s PL/pgSQL
Boolean logic:
BIT
vsBOOLEAN
requires data normalization
Manual conversion risks conversion errors, data loss, or incompatible queries.
Step-by-Step Migration Process
Assess and inventory: List all SQL Server objects to migrate.
Schema conversion: Map tables, indexes, constraints using AI2sql for accurate PostgreSQL code generation.
Data type mapping: Convert columns to PostgreSQL-native types.
Query and procedure translation: Use AI2sql to refactor queries, joins, and functions.
Data migration: ETL tools or scripts for reliable data replication.
Testing: Validate queries, edge cases, and transaction accuracy.
Optimization: Tune indexes and performance settings for PostgreSQL.
AI2sql: Generate PostgreSQL Queries from Natural Language
AI2sql streamlines SQL Server to PostgreSQL conversion by:
Accepting English-language instructions or legacy SQL Server code
Transforming logic and syntax for the PostgreSQL target environment
Supporting 15+ databases and all major SQL dialects
Delivering instant, error-free PostgreSQL statements
Skip manual conversion - Generate PostgreSQL queries instantly with AI2sql using natural language.
Performance Considerations
Index usage: Rebuild indexes for PostgreSQL to optimize query speed
Connection pooling: Leverage PostgreSQL’s robust pooling solutions for high concurrency
Vacuum and analyze: Use regularly to maintain data health and performance
Schema Migration Best Practices
Primary and foreign keys: Validate enforcement of referential integrity
Explicit constraints: Migrate CHECK, UNIQUE, and NOT NULL constraints accurately
Reserved keywords: Rename columns/tables to avoid collisions in PostgreSQL
Testing and Validation
Develop automated unit and regression tests for business logic
Validate row/column counts and data accuracy after migration
Use EXPLAIN ANALYZE to compare query plans and optimize as needed
Rollback Strategies
Take full logical backups pre-migration
Stage migrations in a test environment before production cutover
Create migration scripts with version control for repeatability
Troubleshooting Common Conversion Errors
Unrecognized data types: Map them manually or use AI2sql’s auto-mapping suggestions
Syntax errors: Review function names and string operations
Constraint failures: Ensure data matches new UNIQUE/NOT NULL requirements
PostgreSQL Performance Optimization Tips
Use appropriate
INDEX
types: B-tree, Hash, or GIN for specific workloadsPartition large tables for faster queries
Tune
work_mem
,maintenance_work_mem
, andshared_buffers
5 Practical SQL Server to PostgreSQL Conversion Examples
Description | SQL Server | PostgreSQL |
---|---|---|
Top N Rows | ||
Datetime Conversion | ||
String Concatenation | ||
Auto-Increment Key | ||
Conditional Logic |
Conversion Examples: Syntax at a Glance
Operation | SQL Server | PostgreSQL |
---|---|---|
Select with Alias | ||
Left Join | ||
Date Function | ||
UUID Generation |
For more, explore our PostgreSQL SQL Tutorial.
Why Use AI2sql for Enterprise-Grade SQL Migration?
Supports all major databases and SQL dialects
No syntax expertise required – just describe your logic
Error-free conversions save time and prevent costly mistakes
Used by 50,000+ developers and DBAs for secure, high-accuracy migrations
Scalable for small projects and global enterprises
See more SQL Server Migration Tools to complement your migration journey.
The AI2sql platform delivers production-grade migration capabilities, from simple query rewriting to complex stored procedure conversions and end-to-end database modernization.
Skip manual conversion - Generate PostgreSQL queries instantly with AI2sql using natural language.
Conclusion: Make Your SQL Server to PostgreSQL Migration Error-Free
Migrating from SQL Server to PostgreSQL unlocks modern data agility, but it’s fraught with complexity, syntax pitfalls, and risk of human error. AI2sql transforms this challenge into a seamless process: rapidly converting SQL Server queries and schema to PostgreSQL, adapting data types, and restructuring business logic with production-grade precision. For teams seeking simplicity without sacrificing accuracy, AI2sql is the migration tool of choice.
Try AI2sql Free - Generate PostgreSQL Queries from Plain English
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