1  DISCONNECT
   Detaches from declared databases and releases the aliases that
   you specified in the declarations. The DISCONNECT statement also
   ends the specified transactions and undoes all the changes you
   made since those transactions began.
 

2  Environment
   You can use the DISCONNECT statement:

   o  In interactive SQL

   o  Embedded in host language programs to be precompiled

   o  As part of a procedure in an SQL module

   o  In dynamic SQL as a statement to be dynamically executed
 

2  Format

 DISCONNECT ---+-> <connection-name> -+->
               +-> ALL ---------------+
               +-> CURRENT -----------+
               +-> DEFAULT -----------+
 



 connection-name =
 
 -+--> ' <literal> ' -------+---->
  +--> <parameter> ---------+
  +--> <parameter-marker> --+
 

 

2  Arguments
 

3  ALL

   Specifies all active connections.
 

3  connection-name

   Specifies a name for the association between the group of
   databases being attached (the environment) and the database and
   queries that reference them (the session).

   You can specify the connection name as the following:

   o  A string literal enclosed in single quotation marks

   o  A parameter (in module language)

   o  A variable (in precompiled SQL)
 

3  CURRENT

   Specifies the current connection.
 

3  DEFAULT

   Specifies the default connection.
 

2  Examples
   Example 1: Using the DISCONNECT statement in interactive SQL

   This example in interactive SQL illustrates that the DISCONNECT
   statement lets you attach a database with the same alias as a
   previously attached database (in this example the alias is the
   default). Use the SHOW DATABASE statement to see the database
   settings.

   SQL> ATTACH 'FILENAME mypers';
   SQL> --
   SQL> ATTACH 'FILENAME mypers';
   This alias has already been declared.
   Would you like to override this declaration (No)? no
   %SQL-F-DEFDBDEC, A database has already been declared with the default alias
   SQL> DISCONNECT DEFAULT;
   SQL> ATTACH 'FILENAME mypers';

   Example 2: Using the DISCONNECT statement in precompiled SQL

   This example is taken from the sample program sql_connections.sc.
   To use connections in a program, you must specify the
   SQLOPTIONS=(CONNECT) qualifier on the precompiler command
   line. This example shows an EXEC SQL DISCONNECT statement that
   specifies the string literal 'al' for the connection-name and
   EXEC SQL DISCONNECT statements that specify the keywords ALL and
   DEFAULT.

   #include <stdio.h>
   #include <string.h>
   #include <descrip.h>

   char   employee_id1[6];
   char   last_name1[16];
   char   employee_id2[16];
   char   degree[14];
   char   employee_id3[16];
   char   supervisor[6];
   char   employee_id4[6];
   char   last_name4[15];

   void sys$putmsg();

    EXEC SQL INCLUDE SQLCA;
    EXEC SQL declare         alias filename personnel;
    EXEC SQL declare alias_1 alias filename personnel;
    EXEC SQL declare alias_2 alias filename personnel;
    EXEC SQL declare alias_3 alias filename personnel;
    main()

    {
     printf("\n\n\n******* Disconnect from default ***************\n");
     EXEC SQL disconnect default;
     if (SQLCA.SQLCODE != 0) SYS$PUTMSG(&RDB$MESSAGE_VECTOR,0,0,0);
    printf("\n\n\n");

    printf("********* Establish CONNECTION 1 **********\n");

    EXEC SQL connect to 'alias alias_1 filename personnel' as 'a1';
    if (SQLCA.SQLCODE !=  0) SYS$PUTMSG(&RDB$MESSAGE_VECTOR,0,0,0);

    printf("********* Insert a record  **********\n");

    EXEC SQL insert into alias_1.employees (employee_id, last_name)
    values ('00301','FELDMAN');
     if (SQLCA.SQLCODE != 0) SYS$PUTMSG(&RDB$MESSAGE_VECTOR,0,0,0);

    printf("********* Retrieve the record  **********\n");
    EXEC SQL select employee_id, last_name into :employee_id1,
    :last_name1 from alias_1.employees where employee_id = '00301';
     if (SQLCA.SQLCODE != 0) SYS$PUTMSG(&RDB$MESSAGE_VECTOR,0,0,0);
    printf("\n\n\n");
    printf ("Employee_id = %s\n",employee_id1);
    printf ("Last_name   = %s\n",last_name1);
    printf("\n\n\n");

    printf("********* Establish CONNECTION 2 **********\n");
    EXEC SQL connect to 'alias alias_2 filename personnel' as 'a2';
     if (SQLCA.SQLCODE != 0) SYS$PUTMSG(&RDB$MESSAGE_VECTOR,0,0,0);

    printf("********* Insert a record  **********\n");
    EXEC SQL insert into alias_2.degrees (employee_id, degree_field)
    values ('00901','MASTERS');
     if (SQLCA.SQLCODE != 0) SYS$PUTMSG(&RDB$MESSAGE_VECTOR,0,0,0);

    printf("********* Retrieve the record  **********\n");
    EXEC SQL select employee_id, degree_field into :employee_id2,
    :degree from alias_2.degrees where employee_id = '00901';
     if (SQLCA.SQLCODE != 0) SYS$PUTMSG(&RDB$MESSAGE_VECTOR,0,0,0);
    printf("\n\n\n");
    printf("Employee-id  = %s\n",employee_id2);
    printf("Degree       = %s\n",degree);
    printf("\n\n\n");

    printf("********* Establish CONNECTION 3 **********\n");
    EXEC SQL connect to 'alias alias_3 filename personnel' as 'a3';
     if (SQLCA.SQLCODE != 0) SYS$PUTMSG(&RDB$MESSAGE_VECTOR,0,0,0);

    printf("********* Insert a record  **********\n");
    EXEC SQL insert into alias_3.job_history (employee_id, supervisor_id)
    values ('01501','Brown');
     if (SQLCA.SQLCODE != 0) SYS$PUTMSG(&RDB$MESSAGE_VECTOR,0,0,0);

    printf("********* Retrieve the record  **********\n");
    EXEC SQL select employee_id, supervisor_id into :employee_id3,
    :supervisor from alias_3.job_history where employee_id = '01501';
     if (SQLCA.SQLCODE != 0) SYS$PUTMSG(&RDB$MESSAGE_VECTOR,0,0,0);
    printf("\n\n\n");
    printf("Employee-id  = %s\n",employee_id3);
    printf("Supervisor   = %s\n ",supervisor);
    printf("\n\n\n");

    printf("********* Establish CONNECTION DEFAULT **********\n");
    EXEC SQL set connect default ;
     if (SQLCA.SQLCODE != 0) SYS$PUTMSG(&RDB$MESSAGE_VECTOR,0,0,0);

    printf("********* Retrieve record with id 00164 **********\n");
    EXEC SQL select employee_id, last_name into :employee_id4,
    :last_name4 from employees where employee_id = '00164';
     if (SQLCA.SQLCODE != 0) SYS$PUTMSG(&RDB$MESSAGE_VECTOR,0,0,0);
    printf("\n\n\n");
    printf("Employee_id  = %s\n",employee_id4);
    printf("Last_name    = %s\n",last_name4);
    printf("\n\n\n");

    printf("**** DISCONNECT, RECONNECT & TRY TO FIND RECORD *****\n");
    strcpy(employee_id1,"     ");
    strcpy(last_name1,"              ");
    EXEC SQL disconnect 'a1';
     if (SQLCA.SQLCODE != 0) SYS$PUTMSG(&RDB$MESSAGE_VECTOR,0,0,0);
    EXEC SQL connect to 'alias alias_1 filename personnel' as 'a1';
     if (SQLCA.SQLCODE != 0) SYS$PUTMSG(&RDB$MESSAGE_VECTOR,0,0,0);
    printf("********* Retrieve the record  **********\n");
    EXEC SQL select employee_id, last_name into :employee_id1,
    :last_name1 from alias_1.employees where employee_id = '00301';
     if (SQLCA.SQLCODE != 0) SYS$PUTMSG(&RDB$MESSAGE_VECTOR,0,0,0);

    printf("************** SHOULD DISPLAY NO RECORD **************\n");
    printf("\n\n\n");
    printf("employee_id = %s\n",employee_id1);
    printf("last_name   = %s\n",last_name1);
    printf("\n\n\n");
     printf("*************** DISCONNECT ALL CONNECTIONS ***************\n");
    EXEC SQL disconnect all;
     if (SQLCA.SQLCODE != 0) SYS$PUTMSG(&RDB$MESSAGE_VECTOR,0,0,0);
    EXEC SQL rollback;
   }