– (Subtract/Negative)

Indicates a negative value (unary -) or subtracts one value from another.

Syntax

[expression1] – expression2

The minus sign (-) subtracts the expression on the right from the expression on the left.

where

Comments

Arithmetic operators indicate the sign of a number or perform arithmetic operations (addition, subtraction, multiplication, division, exponentiation).

Performs real-time and on-line backups of Zim databases.

Unix Syntax

[nohup] zimbackup [-k] &

Windows NT Syntax

[start] zimbackup [-k]

Parameters

Comments

Zim Backup Server, working together with Zim Server, performs a real-time, online backup of any databases being serviced by Zim Server.

All modifications performed by Zim Server in a given database are subsequently applied to a copy of the database so that, in fact, there are two “live” databases, one which is the real database that Zim Server is managing to serve all users and a second one, which is an exact copy of the first one.

If something happens to the real database, Zim Backup Server can be stopped in the copy database, Zim Server can immediately start running in this copy database and users can reestablish their Zim sessions.

Before starting servicing users, Zim Server applies committed transactions to the backup database and then opens access to users.

Zim Backup can be stopped at any moment and let the backup databases be copied to another place. Later, Zim Backup can be restarted and all modifications to the real databases are applied in succession to the backup databases.

For operational details, refer to Database Backup.

Sends a bitmap image of the screen to print; output is sent to either the clipboard or the standard output printer.

Syntax

$screenprint()

Return Value

Returns “1” ($True) if no errors were detected before the print job was submitted. Otherwise, returns “0” ($False).

See Also

$printersetup

$screensave

PRINT

Ends a transaction and writes all updates to the database.

Syntax

COMMIT WORK

Comments

This command is the SQL equivalent to the ENDTRANSACTION command.

See Also

$InTransaction

BEGIN WORK

ROLLBACK WORK

TRANSACTION

Controls if virtual fields can be output using a LIST command.

Syntax

SET OUTPUT VIRTUALFIELD ON|OFF

Comments

The OUTPUT VIRTUALFIELD option is set ON by default.

Normally, LIST can output virtual fields. To suppress the output of virtual fields, set OUTPUT VIRTUALFIELD to OFF.

See Also

LIST

Obtain the oldest event generated by a COM component.

Syntax

$ObjGetEvent (Object)

Parameters

Return Value

Returns a result as per the specification of the object.

Note: Zim attempts to convert to the assigned type. Ensure a proper variable type is assigned.

Comments

COM objects can generate synchronous or asynchronous events. In any case, they will be stacked up until removed by a $ObjGetEvent function invocation. Later, the parameters associated to this event can be queried using the $ObjEventParameter function.

Is up to the programmer’s responsibility to know whether the object raises events and what is the structure of these events.

Example

This example creates a component, runs a specific method and then queries the events by retrieving its parameters:

let vObject = $ObjCreate('MyObject.Anything')
let vResponse = $ObjRunMethod(vObject, 'MyMethod', 'AParameter')
let vResponse = $ObjGetEvent(vObject)
if ($ObjEventName = 'MyEvent')
out $objeventparameter(1)
out $objeventparameter(2)
else
...
endif
let vResponse = $ObjDestroy(vObject)

Warning

COM objects are being discontinued by Microsoft and may not be available in future releases of Zim-X.

Identifies the software that is currently being used.

Syntax

$zimversion

Return Value

A number. Cannot be reset by an application program.

Description

The version number of the software currently being used (e.g., 5.002).

See Also

$ZimOS

$ZimProduct

System Variables

The error code returned from the SQL database.

Syntax

$sqlerrcode

Value

A number. Can be reset by an application program.

Description

A numeric code returned from the SQL database for the last SQL statement executed. For explanation of these error codes, consult the documentation for the particular SQL server.

See Also

$SQLErrMsg

System Variables

Specifies if implicit transactions are to be retried automatically if a deadlock or a time-out occurs.

Syntax

SET AUTORETRY ON|OFF

Comments

The AUTORETRY option is set OFF by default.

When AUTORETRY is ON, implicit transactions that fail because of deadlock or time-outs will be retried until they finally succeed or an internal maximum number of retries is reached (which can be set by the database configuration option “transaction retries”).

If these implicit transactions fail, then an error message is printed.

Indicates the number of records that meet the condition(s) specified in the most recent LOCATE command.

Syntax

$located

Return Value

A number. Can be reset by an application program.

Description

The number of records that met the conditions specified in the most recent LOCATE command.

See Also

LOCATE

System Variables