当说到跟踪SQL语句，有人可能会问起这个功能，也许有人会想到用审计功能，为了跟踪SQL语句，去启用审计功能，会成为一种浪费，或许用户只是想跟踪某一个连接的所有SQL语句呢？
请看简单的示例：
1> set tracefile "d:/abc.txt"
2> go
1> set show_sqltext on
2> set statistics io on
3> go
1> select * from t123
2> go
id col2
----------- --------------------------------
再打开d:\abc.txt，内容如下：
================================================================================
Application Tracing report for spid 26 from application "isql"
run by login "sa" on host "SEAN-E6400"
Tracing started on 2013/02/07 05:15:34.48
================================================================================
2013/02/07 05:15:50.70
No useful sqltext available.
Total writes for this command: 0
End of Batch 4
2013/02/07 05:15:55.28
SQL Text: select * from t123
Table: t123 scan count 1, logical reads: (regular=1 apf=0 total=1), physical reads: (regular=0 apf=0 total=0), apf IOs used=0
Total writes for this command: 0
End of Batch 5
这样看来，还是蛮方便的,索引把上边的on/off开关选项，常用的都列到这里：
1. set show_sqltext
2. set showplan
3. set statistics io
4. set statistics time
5. set statistics plancost
需要说明的是：
set tracefile “
set tracefile "
set tracefile on/off (启用或关闭)
当然，dbcc traceon(100) 也会输出一些跟踪的结果在服务器端。