How Can I Retrieve Database Table and Field Information for ORM Development?

Retrieving Database Table and Field Information

In the pursuit of creating a rudimentary ORM, it is crucial to retrieve a list of database tables and their respective fields. This information forms the foundation for generating class definitions and interacting with the underlying database.

Methodologies for Retrieving Table and Field Data

Using System Stored Procedures (SPs)

The sys.tables and sys.columns system stored procedures in SQL Server provide a comprehensive view of tables and fields within a database. The following query combines these SPs to extract the desired information:

SELECT T.name AS Table_Name,
       C.name AS Column_Name,
       P.name AS Data_Type,
       C.max_length AS Size,
       CAST(P.precision AS VARCHAR) + '/' + CAST(P.scale AS VARCHAR) AS Precision_Scale
FROM sys.objects AS T
       JOIN sys.columns AS C ON T.object_id = C.object_id
       JOIN sys.types AS P ON C.system_type_id = P.system_type_id
WHERE T.type_desc = 'USER_TABLE';

This query retrieves table names, column names, data types, column sizes, and precision and scale information.

Accessing Information Schema Views

Another approach is to leverage the INFORMATION_SCHEMA views. These views provide a standardized interface for accessing metadata across different database platforms. The following query uses the COLUMNS view:

SELECT TABLE_SCHEMA,
       TABLE_NAME,
       COLUMN_NAME,
       ORDINAL_POSITION,
       COLUMN_DEFAULT,
       DATA_TYPE,
       CHARACTER_MAXIMUM_LENGTH,
       NUMERIC_PRECISION,
       NUMERIC_PRECISION_RADIX,
       NUMERIC_SCALE,
       DATETIME_PRECISION
FROM INFORMATION_SCHEMA.COLUMNS;

Additional Resources

For your ORM development, consider exploring these informative SQL Server blogs:

• [DBALink](http://dbalink.wordpress.com/2008/10/24/querying-the-object-catalog-and-information-schema-views/)

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