disconnect

Closes one or more connections to a Adaptive Server.

exec sql disconnect 
 {connection_name | current | DEFAULT | all};

DEFAULT: Specifies that the default connection is to be closed. This keyword must be in uppercase letters if you specify the default connection_name using a character string variable, for example:

exec sql disconnect :hv;

#include <stdio.h>

 exec sql include sqlca;

 main()

         exec sql begin declare section;

         CS_CHAR servname[31], username[31],

         password[31], conname[129];

         exec sql end declare section;

         exec sql whenever sqlerror call error_handler();

         exec sql whenever sqlwarning call error_handler();

         exec sql whenever not found continue;

         printf ("Username: ");

         gets   (username);

         printf ("Password: ");

         gets   (password);

         printf ("Adaptive Server name: ");

         gets   (servname);

         printf ("Connection name: ");

         gets   (conname);

/*

 ** Make a named connection.

*/

         exec sql connect :username identified by :password

                 at :conname using :servname;

/*

 ** Make an unnamed (default) connection.

*/

         exec sql connect :username identified by :password

                 using :servname;

/*

 ** The second (default) connection is the current connection.

*/

         exec sql disconnect current;

/*

 ** We now have neither a default connection nor a current one.

*/

         exec sql disconnect :conname;

/*

 ** Now there are no open connections.

*/

         exec sql exit;

 error_handler()

         printf("%d\n%s\n",sqlca.sqlcode,sqlca.sqlerrm.sqlerrmc);

         exit(0);

By itself, the disconnect keyword is not a valid statement. Instead, it must be followed by connection_name, current, DEFAULT, or all.
Closing a connection releases all memory and resources associated with that connection.
disconnect does not commit current transactions; it rolls them back. If an unchained transaction is active on the connection, disconnect rolls it back, ignoring any savepoints.
Closing a connection closes open cursors, drops temporary Adaptive Server objects, releases any locks the connection has in the Adaptive Server, and closes the network connection to the Adaptive Server.