SQL Server – List all tables and the fragmentation percentage

This is another check you should perform once databases start to get large, as having fragmented indexes have a huge performance hit.

For more on what fragmented indexes are, read this fantastic article.

After significant trial and error we have come up with an SQL script that lists all indexes for every table and shows the percentage fragmentation for the selected database on your server in one go!

 

SELECT
a.database_id,
db_name(a.database_id) As DatabaseName,
a.page_count,
a.OBJECT_ID,
a.index_id,
b.name,
a.avg_fragmentation_in_percent
FROM
sys.dm_db_index_physical_stats (DB_ID(), NULL, NULL, NULL, NULL) AS a
INNER JOIN sys.indexes AS b ON a.OBJECT_ID = b.OBJECT_ID AND a.index_id = b.index_id
WHERE
a.database_id = DB_ID()
ORDER BY
a.OBJECT_ID

SQL Server – checking if any tables don’t have a primary key

Its easily done, in the rush to create tables someone forgets to tell the auto-number field that it is also a primary key.

Its not an issue until the database gets big, at which point (as listed on Microsoft TechNet) the performance can suffer by anything between 13% and 460% – which is potentially crippling for your database.

Thankfully there is a simple SQL script you can run to double-check that there are no tables without a primary key.

SELECT SCHEMA_NAME(schema_id) AS SchemaName,name AS TableName
FROM sys.tables
WHERE OBJECTPROPERTY(OBJECT_ID,’TableHasPrimaryKey’) = 0
ORDER BY SchemaName, TableName;

SQL Adding Row Number To The Returned Rows

Its something that took a bit of finding, but is very simple to do. I wanted to automatically add a row number to returned rows from a table in a database

e.g.

SELECT FirstNames, LastName, DOB FROM Staff ORDER BY FirstNames ASC

returns

FirstNames LastName DOB
Richard Taylor 01/01/1980
James Watts 01/01/1980
Richard Stringer 01/01/1980

we can modify this so that it returns a row number by changing the SQL as follows:

SELECT ROW_NUMBER() OVER (ORDER BY FirstNames) As RowNumber, FirstNames, LastName, DOB FROM Staff ORDER BY FirstNames ASC

now returns

RowNumber FirstNames LastName DOB
1 Richard Taylor 01/01/1980
2 James Watts 01/01/1980
3 Richard Stringer 01/01/1980

NB. The ROW_NUMBER() Requires that the over keyword be included after it, and that the order you choose should be the same as the order by on the query.

If you know how to do this in a different way, or a way that will work for a query that does not have an order by (a very rare occurence) then please do post a comment to let others know.