SQL Server Schema Migrations: A Practical Guide
Learn ALTER TABLE syntax, identity columns, bracket quoting, and how to diff MSSQL schemas safely.
Paste two Azure SQL Database schema scripts. Spot every table, column, index, and constraint change instantly. Get ready-to-run ALTER TABLE scripts for Azure SQL — all in your browser.
No account required. No data leaves your device.
SchemaLens understands Azure SQL-specific syntax that generic diff tools miss.
Correctly detects IDENTITY(1,1) columns, seed changes, and increment modifications across Azure SQL schema versions.
Handles bracket-quoted identifiers ([table name]) exactly like Azure SQL does, preserving spaces and reserved words.
Primary keys, unique constraints, foreign keys, CHECK constraints, and CLUSTERED/NONCLUSTERED indexes — all compared semantically.
Generates DF_table_column convention names for default constraints, saving you from manual lookup.
Preserves NVARCHAR, NCHAR, and NTEXT types with length specifications so your Azure SQL migrations stay exact.
Your schema never leaves the browser. Compare production Azure SQL schemas safely without uploading to any third-party server.
Use Azure Data Studio, SSMS, or sqlpackage to extract the database schema from both Azure SQL databases.
Copy the SQL into the two editor panes. Dialect is automatically set to SQL Server (Azure SQL compatible).
See added tables, dropped columns, type changes, and constraint modifications highlighted in color.
Export ALTER TABLE scripts, save as Markdown, PDF, or raw SQL. Run in staging, then production.
SchemaLens generates production-ready ALTER TABLE scripts for every change it detects.
ALTER TABLE [users]
ALTER COLUMN [bio] NVARCHAR(500);
ALTER TABLE [orders]
ADD [shipped_at] DATETIME;
ALTER TABLE [comments]
ADD CONSTRAINT [fk_comments_post]
FOREIGN KEY ([post_id]) REFERENCES [posts]([id]);
ALTER TABLE [tasks]
ADD CONSTRAINT [DF_tasks_status]
DEFAULT 'pending' FOR [status];
Learn ALTER TABLE syntax, identity columns, bracket quoting, and how to diff MSSQL schemas safely.
8 practical differences that trip up developers switching between databases.
Learn how to catch dropped columns, missing indexes, and type changes before they cause incidents.
Join thousands of developers who use SchemaLens to catch schema changes before they hit production.
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