How to View Schema in SQL Server

Galaxy Glossary

How do I view a table schema in SQL Server?

In SQL Server, viewing a schema means querying system catalog views or INFORMATION_SCHEMA objects to list tables, columns, data types, and constraints.

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Description

Why would I want to view a schema in SQL Server?

Developers verify column names, data types, and relationships before writing joins or migrations. Accurate schema knowledge prevents runtime errors and boosts query speed.

Which catalog views expose schema details?

sys.tables, sys.columns, sys.foreign_keys, and sys.indexes offer the most detail. INFORMATION_SCHEMA.TABLES and INFORMATION_SCHEMA.COLUMNS provide ANSI-standard subsets.

How do I list all tables?

Run SELECT name FROM sys.tables ORDER BY name; to return every user table regardless of schema.

How do I describe a single table?

Use sp_help 'dbo.Customers'; or query sys.columns WHERE object_id = OBJECT_ID('dbo.Customers'); to list column definitions, keys, and indexes.

How can I see data types and nullability only?

SELECT column_name, data_type, is_nullable FROM INFORMATION_SCHEMA.COLUMNS WHERE table_name = 'Customers'; keeps output concise.

What is the exact syntax for viewing a table schema?

Syntax varies by object, but the pattern is: SELECT * FROM sys.catalog_view WHERE filter; or EXEC sp_help 'schema.table';. Both accept fully qualified table names.

Practical example: describe the Customers table

To audit customer emails, run SELECT c.name AS column_name, t.name AS data_type, c.max_length FROM sys.columns c JOIN sys.types t ON c.user_type_id = t.user_type_id WHERE c.object_id = OBJECT_ID('dbo.Customers');.

Best practices when inspecting schemas

Always qualify table names with schema (dbo.Customers) to avoid name collisions. Prefer catalog views for complete metadata and INFORMATION_SCHEMA for portability. Script findings into version control.

Common mistakes and quick fixes

Not all metadata lives in INFORMATION_SCHEMA; use sys objects for computed columns and temporal tables. Another pitfall is forgetting OBJECT_ID; wrap table names in quotes and use schema prefixes.

Why How to View Schema in SQL Server is important

How to View Schema in SQL Server Example Usage


--Describe the Orders table, focusing on date and amount columns
SELECT c.name        AS column_name,
       ty.name       AS data_type,
       c.is_nullable,
       c.column_id
FROM   sys.columns c
JOIN   sys.types   ty ON c.user_type_id = ty.user_type_id
WHERE  c.object_id = OBJECT_ID('dbo.Orders')
  AND  c.name IN ('order_date', 'total_amount');

How to View Schema in SQL Server Syntax


--Using INFORMATION_SCHEMA
SELECT *
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_SCHEMA = 'dbo' AND TABLE_NAME = 'Customers';

--Using catalog views
SELECT t.name   AS table_name,
       c.name   AS column_name,
       ty.name  AS data_type,
       c.max_length,
       c.is_nullable
FROM   sys.tables  AS t
JOIN   sys.columns AS c ON t.object_id = c.object_id
JOIN   sys.types   AS ty ON c.user_type_id = ty.user_type_id
WHERE  t.name = 'Customers' AND SCHEMA_NAME(t.schema_id) = 'dbo';

Common Mistakes

Using SELECT * FROM INFORMATION_SCHEMA.COLUMNS without schema filter—returns duplicate table names if multiple schemas exist. Fix by adding TABLE_SCHEMA = 'dbo'.
Relying solely on INFORMATION_SCHEMA for computed columns; it omits them. Use sys.columns and sys.computed_columns to capture computed and persisted fields.

Frequently Asked Questions (FAQs)

Does INFORMATION_SCHEMA work in Azure SQL Database?

Yes, Azure SQL supports INFORMATION_SCHEMA views, but features like memory-optimized tables may require sys views for full details.

Can I script a table definition from the catalog?

Yes. Use SQL Server Management Studio’s “Script Table as” feature or query sys.sql_modules for stored procedure definitions.

Is sp_help deprecated?

No. sp_help remains supported, but Microsoft recommends sys catalog views for advanced metadata such as temporal history tables.

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