Connecting Query to a Data Server

Before commands can be sent from Query to any data server, a link must be set up between the two.

1. To connect Query to a data server which is installed on the same machine, use one of the following commands:

   EXTERnal OPEn synonym token_var

   EXTERnal OPEn synonym token_var [AS connect_string]

   Where:

   • synonym = A text string which identifies the server daemon through which communication is to be channelled (and which therefore identifies the data server required).

   • token_var = The name of a PML variable into which a token for the connection is to be written.

   • (If your data server requires login data) connect_string = A text string which confirms the users access rights (such as their username and password).

     Examples:

     EXTERNAL OPEN ’MAINTENANCE’ !!MAINT AS ’bull/robert’

     or

     EXTERNAL OPEN ’ODBC’ !!MAINT AS ’DSN=MAINTDAT;’

2. To connect Query to a data server which is installed on a different machine, use the extended form of the command:

   EXTERnal OPEn synonym token_var ON host [AS connect_string]

   Where synonym, token_var and connect_string are as above.

   host = a text string which identifies the node on the network on which the server daemon. For example, to connect to a data server on a machine called pc35, enter

   EXTERNAL OPEN ’MAINTENANCE’ !!MAINT ON ’pc35’ AS ’bull/robert’

   or, alternatively, a generalised version such as

   EXTERNAL OPEN ’MAINTENANCE’ !!MAINT ON ’sqlnet’ AS ’bull/robert’

   Where the alias ‘sqlnet’ has been defined so as to point to the current host for, say, an SQL database server.

3. To disconnect Query from a data server to which it is currently connected, use the command

   EXTERnal CLOse token

   Where:

   • token = The token for the communication channel which was supplied by a successful EXTERNAL OPEN command (and stored in the token_var variable).

     Example:

     EXTERnal CLOse $!!MAINT

     Note: The $ prefix used to expand the variable !!MAINT to give the token value.