Posted on May 7, 2012
Finding crap in the SQL Server database
Anyone who has ever maintained an old legacy code base often finds themselves working with a decade old database schema that now spans hundreds of tables, each of which contain dozens of columns. Trying to locate a particular column or table in the db can be particularly difficult, especially if the only clue you have is a vague inkling of what said table/column might be named. Luckily, SQL Server provides several system tables that hold metadata that can help you find the proverbial needle in the haystack.
We can query sys.tables and sys.columns like so:
--look for a particular table
SELECT t.name AS table_name
FROM sys.tables AS t
WHERE t.name LIKE '%needle%'
--look for a particular column
SELECT t.name AS table_name,
c.name AS column_name
FROM sys.tables AS t
JOIN sys.columns c
ON t.OBJECT_ID = c.OBJECT_ID
WHERE c.name LIKE '%needle%'
ORDER BY table_name;
The information_schema.columns table lets you accomplish the same thing. This table shares a lot of the same information as sys.columns (but does not contain the object_id), but it already contains the table_name so you don’t have to do a join. This is good if you are lazy and dislike typing more than necessary.
SELECT TABLE_NAME, COLUMN_NAME
WHERE COLUMN_NAME LIKE '%needle%'
ORDER BY TABLE_NAME;
These queries provide a good starting point for exploring the database and all the metadata available to you. Of course, if you’re too lazy to do any typing at all, you can simply open SQL Server Management Studio, click on “View” in the menus, and select Object Explorer Details. From there you can do a search. Its important to note that this searches EVERYTHING. Views, stored procedures, triggers, tables, columns, and everything else that is an object in SQL Server.
If you run the profiler, you can see that it is indeed querying all the system tables, including sys.database_principals, sys.asymmetric_keys, and sys.all_objects.
Often times this UI search will get the job done, although it can produce a lot of noise.