To migrate from MSSQL to MYSQL, Please use MYSQL Migration Toolkit
To download and use the MYSQL Migration Toolkit, Please use the following link http://dev.mysql.com/downloads/gui-tools/5.0.html
The MySQL Workbench Migration Wizard is designed to save DBA and developer time by providing visual, point and click ease of use around all phases of configuring and managing a complex migration process:
Database migrations - enables migrations from Microsoft SQL Server, PostgreSQL, Sybase ASE, Sybase SQL Anywhere, SQLite, and more.
Migration project management - allows migrations to be configured, copied, edited, executed and scheduled.
Source and Target selection - allows users to define specific data sources and to analyze source data in advance of the migration.
Object migration - allows users to select objects to migrate, assign source to target mappings where needed, edit migration scripts and create the target schema.
Data migration - allows users to map source and target data and data types, set up data transfer and assign post data transfer events where needed.
Version Upgrades - using migration users can easily move databases off older MySQL versions to the latest.