Hidden Features of SQL Server

Question

In Management Studio, you can put a number after a GO end-of-batch marker to cause the batch to be repeated that number of times:

PRINT 'X'
GO 10

Will print 'X' 10 times. This can save you from tedious copy/pasting when doing repetitive stuff.

A lot of SQL Server developers still don't seem to know about the OUTPUT clause (SQL Server 2005 and newer) on the DELETE, INSERT and UPDATE statement.

It can be extremely useful to know which rows have been INSERTed, UPDATEd, or DELETEd, and the OUTPUT clause allows to do this very easily - it allows access to the "virtual" tables called inserted and deleted (like in triggers):

DELETE FROM (table)
OUTPUT deleted.ID, deleted.Description
WHERE (condition)

If you're inserting values into a table which has an INT IDENTITY primary key field, with the OUTPUT clause, you can get the inserted new ID right away:

INSERT INTO MyTable(Field1, Field2)
OUTPUT inserted.ID
VALUES (Value1, Value2)

And if you're updating, it can be extremely useful to know what changed - in this case, inserted represents the new values (after the UPDATE), while deleted refers to the old values before the UPDATE:

UPDATE (table)
SET field1 = value1, field2 = value2
OUTPUT inserted.ID, deleted.field1, inserted.field1
WHERE (condition)

If a lot of info will be returned, the output of OUTPUT can also be redirected to a temporary table or a table variable (OUTPUT INTO @myInfoTable).

Extremely useful - and very little known!

Marc

sp_msforeachtable: Runs a command with '?' replaced with each table name. e.g.

exec sp_msforeachtable "dbcc dbreindex('?')"

You can issue up to 3 commands for each table

exec sp_msforeachtable
    @Command1 = 'print ''reindexing table ?''',
    @Command2 = 'dbcc dbreindex(''?'')',
    @Command3 = 'select count (*) [?] from ?'

Also, sp_MSforeachdb

Connection String extras:

MultipleActiveResultSets=true;

This makes ADO.Net 2.0 and above read multiple, forward-only, read-only results sets on a single database connection, which can improve performance if you're doing a lot of reading. You can turn it on even if you're doing a mix of query types.

Application Name=MyProgramName

Now when you want to see a list of active connections by querying the sysprocesses table, your program's name will appear in the program_name column instead of ".Net SqlClient Data Provider"

TableDiff.exe

• Table Difference tool allows you to discover and reconcile differences between a source and destination table or a view. Tablediff Utility can report differences on schema and data. The most popular feature of tablediff is the fact that it can generate a script that you can run on the destination that will reconcile differences between the tables.

Link