After installed SQL Server 2008, in order to check whether can establish database connection, checking whether the isql command can be executed normally. It will prompt the connection checking failed.
SQL Server 2008 uses osql instead of isql function, in order to be compatible with the old version, can through the following ways to continue to use the isql command available:
Enter the “\100\Tools\Binn” directory of SQL Server installation directory, copy osql and renamed it to isql.
Enter the “\100\Tools\Binn\Resources\1033” directory of SQL Server installation directory, copy osql.rll and renamed it to isql.rll.
The problem will be solved.