MySQL to MS SQL: Best Practices for Schema Conversion

Data type mismatches between MySQL and MS SQL Server occur because the two database engines use different storage architectures and keyword definitions. Resolving these mismatches requires mapping incompatible data types, adjusting size limits, and rewriting specialized attributes. Core Data Type Mapping Guide

This list shows the standard mappings required to convert MySQL types to their MS SQL equivalents. MySQL INT →right arrow MS SQL INT MySQL BIGINT →right arrow MS SQL BIGINT MySQL VARCHAR(N) →right arrow MS SQL VARCHAR(N) MySQL TEXT →right arrow MS SQL VARCHAR(MAX) MySQL LONGTEXT →right arrow MS SQL VARCHAR(MAX) MySQL BLOB →right arrow MS SQL VARBINARY(MAX) MySQL LONGBLOB →right arrow MS SQL VARBINARY(MAX) MySQL DATETIME →right arrow MS SQL DATETIME2 MySQL TIMESTAMP →right arrow MS SQL DATETIME2 MySQL DOUBLE →right arrow MS SQL FLOAT(53) Critical Incompatibilities and Fixes The Timestamp Trap

The Issue: MySQL TIMESTAMP tracks date and time. MS SQL TIMESTAMP is a binary counter for row versioning, not a date. The Fix: Map MySQL TIMESTAMP to MS SQL DATETIME2. Unsigned Integers

The Issue: MySQL supports INT UNSIGNED (0 to 4,294,967,295). MS SQL integers are strictly signed (-2,147,483,648 to 2,147,483,647).

The Fix: Upgrade the data type size in MS SQL. Change INT UNSIGNED to BIGINT. Zero Dates

The Issue: MySQL allows invalid dates like 0000-00-00. MS SQL DATETIME2 has a minimum valid date of 0001-01-01.

The Fix: Scrub the MySQL data before migration. Convert all 0000-00-00 entries to NULL or a placeholder like 1970-01-01. Boolean Representations

The Issue: MySQL treats BOOLEAN as an alias for TINYINT(1) using 1 and 0. MS SQL uses the BIT data type.

The Fix: Map TINYINT(1) columns to BIT. Ensure migration scripts convert numbers to TRUE/FALSE literals if needed. Auto-Increment Attributes

The Issue: MySQL uses the AUTO_INCREMENT keyword on the column definition. MS SQL uses the IDENTITY(seed, increment) property.

The Fix: Change id INT AUTO_INCREMENT to id INT IDENTITY(1,1). Recommended Migration Tools

Manual conversion is prone to error. Use these automated migration tools to handle structural type mapping:

SSMA (SQL Server Migration Assistant): Free Microsoft tool designed specifically to automate MySQL to MS SQL conversion.

Azure Data Factory: Excellent for cloud-based data movement and schema transformation.

DBeaver / DataGrip: Database IDEs featuring built-in export wizards that handle basic data type conversion. To help tailor this advice, please tell me:

What is the approximate size of the database you are migrating?