System exceptions

System exceptions are error conditions that can occur in any Dexterity-based application. Any operation that automatically displays an error dialog to the user is considered a system exception. Common examples of system exceptions are string overflow errors, division-by-zero errors and database errors.

Like user exceptions, all system exceptions are identified by a class and subclass. Both are long integer values. The classes are divided into three categories: script exceptions, database exceptions and form exceptions. The subclass tyically indicates the sanScript command that caused the exception. If the sanScript command that caused the exception is not known, another appropriate value, such as a table ID or script ID, is provided as the subclass.

The following tables list the classes and subclasses for system exceptions.

Exception class: Script

Class constant	Description
EXCEPTION_CLASS_SCRIPT_ADDRESSING	A referenced item isn’t currently accessible.
EXCEPTION_CLASS_SCRIPT_BAD_TYPE	An incompatible data type was used.
EXCEPTION_CLASS_SCRIPT_DIVIDE_BY_ZERO	A division by zero error occurred.
EXCEPTION_CLASS_SCRIPT_ERROR	A general script error occurred.
EXCEPTION_CLASS_SCRIPT_ILLEGAL_OP	An illegal operation was performed.
EXCEPTION_CLASS_SCRIPT_MEMORY	Not enough memory available to perform the operation.
EXCEPTION_CLASS_SCRIPT_MISSING	A referenced item is missing from the dictionary.
EXCEPTION_CLASS_SCRIPT_OUT_OF_RANGE	A value is outside the acceptable range.

Exception class: Object

Class constant	Description
EXCEPTION_CLASS_OBJECT_EXCEPTION	A COM exception occurred.

Exception class: Form

Class constant	Description
EXCEPTION_CLASS_FORM_MEMORY	There is not enough memory available to load the form.
EXCEPTION_CLASS_FORM_MISSING	The form is missing from the dictionary.
EXCEPTION_CLASS_FORM_SECURITY	Access to a form was denied by the Security global procedure.

Exception class: Database

Class constant	Description
EXCEPTION_CLASS_DB	A general database error occurred.
EXCEPTION_CLASS_DB_CHG_TRAN_LVL	The transaction level was changed in a stored procedure that was called.
EXCEPTION_CLASS_DB_DEADLOCK	A deadlock error occurred while in a transaction.
EXCEPTION_CLASS_DB_TRAN_IMP_ROLLBACK	A script was terminated and left a pending transaction that was rolled back.

Subclasses for script and form exceptions

For most operations, the subclass for a system exception indicates the sanScript command that caused the exception. The following table lists the constants for the common exception subclasses.

Subclass constant	Command or operator
SCRIPT_CMD_ADD	+
SCRIPT_CMD_SUB	-
SCRIPT_CMD_MUL	*
SCRIPT_CMD_DIV	/
SCRIPT_CMD_MOD	%
SCRIPT_CMD_NEG	-
SCRIPT_CMD_POWER	^
SCRIPT_CMD_EQ	=
SCRIPT_CMD_NEQ	<>
SCRIPT_CMD_LT	<
SCRIPT_CMD_LTEQ	<=
SCRIPT_CMD_GT	>
SCRIPT_CMD_GTEQ	>=
SCRIPT_CMD_NOT	not
SCRIPT_CMD_AND	and
SCRIPT_CMD_OR	or
SCRIPT_CMD_XOR	xor
SCRIPT_CMD_LSL	<< or shiftl
SCRIPT_CMD_LSR	>> or shiftr
SCRIPT_CMD_IMP	imp
SCRIPT_CMD_BITTEST	bittest()
SCRIPT_CMD_BITCLEAR	bitclear()
SCRIPT_CMD_BITSET	bitset()
SCRIPT_CMD_ADDMONTH	addmonth()
SCRIPT_CMD_ASK	ask()
SCRIPT_CMD_CALL	call
SCRIPT_CMD_CALLBKG	call background
SCRIPT_CMD_CALLSERVER	call sproc
SCRIPT_CMD_CHANGED	changed()
SCRIPT_CMD_CLEARCHANGE	clear changes
SCRIPT_CMD_CLOSE	close
SCRIPT_CMD_COUNTRECS	countrecords()
SCRIPT_CMD_DELETE	delete
SCRIPT_CMD_EDIT	edit
SCRIPT_CMD_EMPTY	empty()
SCRIPT_CMD_ERROR	error
SCRIPT_CMD_EXECUTE	execute
SCRIPT_CMD_FINDITEM	finditem()
SCRIPT_CMD_FIRST	get first, change first
SCRIPT_CMD_FOCUS	focus
SCRIPT_CMD_FORCECHNG	force change
SCRIPT_CMD_FORCECHNGCLR	clear force change
SCRIPT_CMD_GETSTR	getstring()
SCRIPT_CMD_HEXSTRING()	str()
SCRIPT_CMD_HIDE	hide
SCRIPT_CMD_ISOPEN	isopen()
SCRIPT_CMD_ITEMCOUNT	countitems()
SCRIPT_CMD_ITEMNAME	itemname()
SCRIPT_CMD_LAST	get last, change last
SCRIPT_CMD_MAX	max()
SCRIPT_CMD_MIN	min()
SCRIPT_CMD_MOVEFIELD	move field
SCRIPT_CMD_NATIVEFILEERROR	naterr()
SCRIPT_CMD_NEXT	get next, change next
SCRIPT_CMD_OPEN	open
SCRIPT_CMD_OPENEX	open table, exclusive
SCRIPT_CMD_PRIOR	get prev, change prev
SCRIPT_CMD_RANGEEND	range end
SCRIPT_CMD_RANGESTART	range start
SCRIPT_CMD_REDRAW	redraw
SCRIPT_CMD_RELEASE	release
SCRIPT_CMD_REMOVE	remove
SCRIPT_CMD_REPLACE	replace()
SCRIPT_CMD_REQUIRED	required()
SCRIPT_CMD_RESIZEFIELD	resize field
SCRIPT_CMD_RESTARTFIELD	restart field
SCRIPT_CMD_ROUND SCRIPT_CMD_RNDCURRENCY	round()
SCRIPT_CMD_RUNDELAY	run script delayed
SCRIPT_CMD_RUNSCRIPT	run script
SCRIPT_CMD_SETCURPRECIS SCRIPT_CMD_SETPRECISION	set precision
SCRIPT_CMD_SHOW	show
SCRIPT_CMD_STRING	str()
SCRIPT_CMD_THIS	get, change
SCRIPT_CMD_TRUNCATE SCRIPT_CMD_TRUNCCURRENCY	truncate()
SCRIPT_CMD_UNLOCK	unlock
SCRIPT_CMD_WARNING	warning

The preceding table lists the most common commands and operators that can produce exceptions. If an unlisted command has caused an exception, you can use the exception dialog that is displayed to find out more information about the command that caused the exception. The exception dialog is shown in the following illustration.

Simply scroll down to the end of the message text to see the class and subclass of the exception that was thrown.

Subclasses for database exceptions

The subclass value that is returned for database exceptions indicates the database error that occurred, rather than the sanScript statement that caused the error. The following table lists the constants that correspond to the subclass values returned for database exceptions.

DB_ERR_MEMORY	DB_ERR_DISK_FULL
DB_ERR_NOT_INITIALIZED	DB_ERR_UNKNOWN
DB_ERR_NOT_SUPPORTED	DB_ERR_KEY_CHANGED
DB_ERR_TOO_MANY_OPEN_TABLES	DB_ERR_NOT_VAR_FIELD
DB_ERR_INCORRECT_RECORD_LENGTH	DB_ERR_CHANGED
DB_ERR_TOO_MANY_KEYS	DB_ERR_DEADLOCKED
DB_ERR_TOO_MANY_SEGMENTS	DB_ERR_PATH_NOT_FOUND
DB_ERR_TABLE_NOT_REGISTERED	DB_ERR_BUFFER_MISMATCH
DB_ERR_TABLE_NOT_FOUND	DB_ERR_COULD_NOT_CREATE
DB_ERR_LOCKED	DB_ERR_INCORRECT_NUMBER_OF_KEYS
DB_ERR_BAD_FILENAME	DB_ERR_SQL_TOO_MANY_CONNECTIONS
DB_ERR_TABLE_NOT_OPEN	DB_ERR_SQL_DATA_ACCESS_ERR
DB_ERR_TABLE_NOT_EXCLUSIVE	DB_ERR_SQL_DATA_CONV_ERR
DB_ERR_INVALID_CMD	DB_ERR_SQL_GENERATION_ERR
DB_ERR_INVALID_KEY	DB_ERR_NO_PRIMARY_KEY
DB_ERR_EOF	DB_ERR_SQL_NOT_LOGGED_IN
DB_ERR_DUPLICATE	DB_ERR_CANNOT_INIT_CTREE
DB_ERR_MISSING	DB_ERR_CANNOT_INIT_BTRIEVE
DB_ERR_SET_ALREADY_ACTIVE	DB_ERR_CANNOT_INIT_SQL
DB_ERR_TRANS_IN_PROGRESS	DB_ERR_SQL_OBJ_NOT_FOUND
DB_ERR_NOT_VAR_LENGTH_TABLE	DB_ERR_TRANS_ROLLED_BACK
DB_ERR_TABLE_NOT_DEFINED	DB_ERR_SQL_CONNECTION_ERR
DB_ERR_CANNOT_LOCK_TWO_RECORDS	DB_ERR_STILL_EXECUTING
DB_ERR_RECORD_NOT_LOCKED	DB_ERR_SQL_CONSTRAINT_VIOLATION
DB_ERR_TABLE_DEF_MISMATCH