SqlDoc: Document your SQL Server database

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Introduction

This article presents a small command prompt utility to help you document your SQL Server/MSDE database.

Background

In SQL Server, every property of tables, fields, relations, etc. are stored in a few system tables. You can query those tables to extract info about your database. SQL Server provides a mechanism to simplify the queries to those system tables: Information Schema.

Try to run the command "SELECT * FROM INFORMATION_SCHEMA.columns" in any database. A list of every column in every table in the database will be returned.

I code this utility to auto document my databases, extracting table names, columns names, field types, lengths, and nullable columns, and generate a HTML file with that info. You can tweak the queries to extract any other info that you need.

There is a special piece of info that is not available through Information Schema: column's description field. I find it very useful to fill that field when I design a table, to clarify the purpose of a column. To extract that description, you must bypass Information Schema and query directly the system tables.

How it works

The inner working of this app is very simple. It gets the results of special queries, and writes an XML file which is used in combination with an XSLT file to produce the final HTML file.

Using the code

You can quick test the utility, extracting info about the Northwind database, typing:

SqlDoc.exe -E -d northwind

This will produce the file output.html.

I've tried to mimic the OSQL command switches. The available switches are:

• -E - uses integrated security to connect SQL Server.
• -S server_name - connect to a specific server.
• -U user_id - connect using a user name.
• -P password - self explained.
• -o outputFileName - self explained.

The source code, it's very simple to follow and it's self-describing.

Note that as commented before, in order to extract the column's description field, the code bypasses the standard way to extract columns info. This means that in future releases of SQL Server, the query could fail. If you don't find useful the 'description field', you can comment/uncomment these lines to use the method you want.

// most compatible way to retrieve column info but lacks 
// description field
//private const string SQL_GETFIELDS = "SELECT TABLE_NAME, " +
//    "COLUMN_NAME, COLUMN_DEFAULT, DATA_TYPE, " +
//    "CHARACTER_MAXIMUM_LENGTH, IS_NULLABLE " +
//    "FROM INFORMATION_SCHEMA.Columns " + 
//    "WHERE TABLE_NAME IN (" + SQL_GETTABLES + ")";

// this one gets columns info + the description field
private const string SQL_GETFIELDS = 
    "SELECT Sysobjects.name AS TABLE_NAME, " +
    "syscolumns.Id, syscolumns.name AS COLUMN_NAME, " + 
    "systypes.name AS DATA_TYPE, syscolumns.length" + 
    " as CHARACTER_MAXIMUM_LENGTH, " +
    "sysproperties.[value] AS COLUMN_DESCRIPTION,  " +
    "syscomments.text as COLUMN_DEFAULT, " +
    "syscolumns.isnullable as IS_NULLABLE " +
    "FROM syscolumns INNER JOIN systypes " +
    "ON syscolumns.xtype = systypes.xtype " +
    "LEFT JOIN sysobjects ON syscolumns.id = sysobjects.id " + 
    "LEFT OUTER JOIN sysproperties ON " +
    "(sysproperties.smallid = syscolumns.colid" + 
    " AND sysproperties.id = syscolumns.id) " +
    "LEFT OUTER JOIN syscomments ON syscolumns.cdefault = syscomments.id " +
    "WHERE syscolumns.id IN " + 
    "(SELECT id FROM SYSOBJECTS WHERE xtype = 'U') " + 
    "AND (systypes.name <> 'sysname')" +
    "ORDER BY syscolumns.colid";

Points of Interest

Leaving apart the purpose of this app, I was interested in learning about the XSLT transformations. Included in the demo project is a test XSLT file. You can edit this file in order to improve the output format.

Improvements

SQL Server stores tons of info about each database, relations, key columns, views, stored procedures, etc. So fully documenting the database, it's the way to go.