|
Expressions
Any combination of
variables, operators, constants, functions, and names
of fields, controls, and properties that evaluates to
a single value. You can use expressions as settings
for a control's control source, and to set macros etc.
- The Control name
must be preceded by an '&'. For
example, &age means the form field that
has the name "age".
- A variable must be
proceded by an '@'. For example, @var1 refer
to the variable named "var1".
- If you want to
refer to the value of the table field in another
SubForm, Table field must be proceded by '!n!'.
!n! means SubForm n. For example: !0!table1.field1
refer to the value of the table1.field1 in the
MainForm, and !1!table1.field1 refer to the
value of the table1.field1 in SubForm1.
Operators
Arithmetic
Operators
- '/'
operator causes the first operand to be divided by
the second. For example: table1.int_field / 34,
table1.double_field / &form_field1,
&form_field1 / &form_field2.
- '*'
operator causes its two operands to be multiplied.
For example: 123.456 * 34, 123.456 *
!0!table1.field1, &form_field1 *
!1!table1.dbl_field1.
- '+'
operator causes its two operands to be added. If
the two operands are strings, the '+' operator
appends the second operand to the first. For
example: 30+40, 'abc'+'def',
- '-'
operator subtracts the second operand from the
first. For example: 40-30.
- '%' is the
modulus operator. The result of the operator is
the remainder when the first operand is divided by
the second. For example: 7%4 -> 3.
Comparison
Operators
- '='(Equals)
operator: The result of the operator is 1(TRUE) if
both operands are equal; otherwise, 0(FALSE).
- '>'(Greater
Than) operator: The result of the operator is
1(TRUE) if the first operand has a higher value
than the second; otherwise, 0(FALSE).
- '<'(Less
Than) operator: The result is 1(TRUE) if the first
operand has a lower value than the second;
otherwise, 0(FALSE).
- '>='(Greater
Than or Equal To): The result is 1(TRUE) if the
first operand has a higher or equal value than the
second; otherwise, 0(FALSE).
- '<='(Less
Than or Equal To): The result is 1(TRUE) if the
first operand has a lower or equal value than the
second; otherwise, 0(FALSE).
- '<>','!='(Not
Equal To): The result of the operator is 1(TRUE)
if the first operand is not equal to the second;
otherwise, 0(FALSE).
Logical
Operators
- 'AND'
combines two boolean expressions and returns
1(TRUE) when both of the expressions are TRUE;
otherwise, 0(FALSE).
- 'OR'
combines two boolean expressions and return
1(TRUE) when either of the expressions is TRUE;
otherwise, 0(FALSE).
- 'NOT'
negates a boolean input.
|
|
