OSQL and Difference b/w OSQL and ISQL

Today We Talk About OSQL.

So, what is OSQL?
Thus, OSQL  is an functional query language.The data model of OSQL is object oriented with three kinds of system entities:
                        1. Objects
                        2. Types
                        3. Functions. 

The data model is similar to an ER model with the difference that both entity relationships and attributes which are represented as functions and inheritance among entity.OSQL provide object identifiers which return OIDs as results. Queries are expressed using a SELECT syntax similar to SQL commands.

Difference Between OSQL & ISQL 
There is a great deal of overlap between ISQL and OSQL.Both support input scripts, output scripts, and most of the same switch arguments.

 OSQL scripts

In these next examples, we will create and save TSQL scripts, and then run them from OSQL. Query Analyzer is a standard choice for script creation because of the color coding. Open Query Analyzer and enter:

USE pubs

GO

SELECT * FROM authors

GO

Save this script to your hard drive, and then from the command line, enter an OSQL statement using the -i switch to specify an input file. The authors table should be returned.

OSQL -E -i c:\temp\q1.sql

The results of the query can be captured to an output file, rather than appearing on the screen. Change the command line to include the -o parameter, for output.

OSQL -E -i c:\temp\q1.sql -o c:\temp\resutls.txt

OSQL should create a text output file. The -u switch can be used to control the output file being either Unicode.

System Commands

Operating system commands can also be executed from inside the TSQL script. The key !! is used to specify this. Change the Query Analyzer script and save it as:

!! dir c:\temp

GO

USE pubs

GO

SELECT * FROM authors

GO

Now our output file will include the directory listing of the temp folder in addition to the authors' results. Also, note this script will not run in Query Analyzer. The !! directive is not supported. Query Analyzer color coding is helpful in code layout, but the script testing will need to be done from OSQL.

Error Handling

OSQL supports the RAISERROR command for returning custom error messages. To use raise error, the database name, id, error severity and state should be included. Using RAISERROR will cause the script to terminate. Modify the Query Analyzer script to:

!! dir c:\temp

GO

DECLARE @DBID int

SET @DBID = DB_ID()

DELCARE @DBNAME nvarchar(128)

SET @DBNAME = DB_NAME()

RAISERROR('my error', 18, 127, @DBID, @DBNAME)

USE pubs

GO

SELECT * FROM authors

GO

Running the script will now output our directory listing, from the "!! dir c:\temp" command, followed by the raise error. The remaining script, changing to pubs and selecting from authors will not occur. RAISERROR will terminate the script.

Leaving a script can also be done by calling QUIT or EXIT from inside OSQL. Neither of these will return an error code, but EXIT can execute a statement prior to quitting. For example: EXIT(SELECT @@ROWCOUNT).

Conclusion

When administering the Microsoft Desktop Engine, OSQL is a free way to run statements. For standard SQL Server environments, OSQL can be used to help automate long or repetitive tasks by reusing scripts. OSQL is also a good choice to run database setup scripts during application install procedures