 |
 Avoiding
Error Messages:
When
writing an expression, use the expression builder
(click the X-Y icon) and choose field names and
functions from the lists instead of typing them
in yourself. This will avoid misspellings that
are particularly difficult to catch in long expressions.
Match
the result of the expression to the field you
are using it with. For example, if you make a
date field a calculated field in field rules,
you must be certain your expression will yield
date type data. If necessary, use a converting
function such as CTOD (character type to date
type).
When
using constants in an expression, follow this
guide:
Enclose character string constants in quotations.
Example: DEPT="Accounting"
Enclose date constants in brackets. Example: DUEDATE>={03/31/97}
Enclose logical constants in periods. Example:
PMTRECD=.T.
Don't enclose numeric constants in anything. Example:
AMOUNT=132.56
Troubleshooting
methods:
If
you feel mired in a long and complex expression,
consider making a small test database containing
various field types. Try to break the expression
into smaller problems, testing each piece to
see if it works independently. Then begin to
rebuild the final expression, piece by piece,
checking your results as you go.
Respect
the syntax of each function you use exactly.
If you forget a comma, parenthesis or quotation
mark, Alpha Five will give you an error message.
Check for a closing (right) parenthesis for
every open (left) parenthesis and an even number
of quotation marks. When combining functions
to write a complex expression, check for proper
placement and nesting of parentheses.
Filters:
Filters
must yield a logical result, true or false.
There must be an operator such as = , <, <=, >, >=, <> (not
equals) or $ (contains character string) in
the expression.
Connect
logical expressions with .AND. and .OR. using
parentheses to clarify the relationship between
groups of logical expressions. Example: (STATE="FL".OR.STATE="GA").AND.AMOUNT>=100
IF
statements:
The
IF syntax must contain both a true and a false
result. If you do not wish the false result
to effect a change, simply fill in the same
field name. For example, when globally updating
STATE, the expression IF(UT(CITY)="MIAMI","FL",STATE)
will not change the contents of the state field
unless the city is Miami.
Save
time next time:
Use
the Windows clipboard to copy and paste expressions.
To copy to the clipboard, highlight the expression
(or part of an expression) and press [Ctrl-C].
To paste from the clipboard, position the cursor
where you want to insert the expression and
press [Ctrl-V].
Proctor &
Peake, Inc.
9620 NE 2nd Avenue, Suite 209
Miami Shores, FL 33138
305-751-1181 / 1-800-943-6031
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us
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