OSQL.EXE VS. ISQL.EXE v7.0
In prior versions of SQL Server, ISQL.exe was provided as a way to 
interface to the server via batch files and the command line. The 
creation of Microsoft SQL Server version 7.0 spawned a new command-line 
utility for interfacing to the SQL Server, OSQL.exe.

The main difference between these two command-line utilities is that 
ISQL.exe uses DB-Library as its communication mechanism and OSQL.exe 
uses ODBC. SQL Server 7.0 includes ISQL.exe for the sake of backward-
compatibility, but ISQL 7.0 does not support any of the new features in 
version 7.0. Microsoft recommends that you migrate or develop new 
applications based on OSQL.exe rather than ISQL.exe.

The OSQL.exe takes on the command line format of

c:>osql.exe -S<servername> -U<sa> -P<password>

A notable feature is the ability to specify your password into an 
environment variable, which means you do not have to hard-code your 
password into your SQL scripts. Using the OSQLPASSWORD environment 
variable will allow for a command-line execution of the following.

c:\>set OSQLPASSWORD=mypassword 
c:\>osql.exe -S<servername> -U<sa> 

Note that many of the command-line options are case sensitive.

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