ZIM Language Operators – 4GL APPLICATION FRAMEWORK

[NOT] BETWEEN

Compares one value to a specified range of values.

Syntax

expression [NOT] BETWEEN expr1 AND expr2

Parameters

expression	An expression that evaluates to either a number or a character string.
expr1	An expression that evaluates to either a number or a character string.
expr2	An expression that evaluates to either a number or a character string.

Return Value

Logical

Comments

If any one of expression, expr1, and expr2 is a number, then a numeric comparison is made; otherwise, the comparison is character-based. Note that the AND in a BETWEEN comparison is not the Boolean AND.

A BETWEEN comparison is logically true if expression is greater than or equal to expr1, and less than or equal to expr2.

A NOT BETWEEN comparison is logically true if expression is either less than expr1, or greater than expr2.

Note: The AND in a BETWEEN comparison is not the Boolean AND.

Example

BioDiversity between 500 and 2000

Logically true if the value of BioDiversity lies between 500 and 2000 (inclusive).

( ) Parentheses

Alters the order of evaluation of expressions, or groups expressions, or both.

Syntax #1

Alters the order of evaluation in expressions.

(expression)

Within a larger expression, a single expression placed in parentheses changes the order of execution (which normally depends on the precedence of operators).

Parameters

expression

an arithmetic or logic expression

Syntax #2

Groups expressions.

(expression1, expression2)

Parentheses can be used to group several expressions, each of which is evaluated; the grouped expression takes on the value of the last individual expression in the group.

Parameters

expression1	any expression
expression2	any expression

Comments

Use parentheses to group one or more expressions, each of which is evaluated. The grouped expression takes on the value of the last expression in the group.

Examples

7 * 8 - 5^2

7 * (8 - 5)^2

not Salary > 30000 or Age < 25

Result: Logically true when Salary is 29,000 and Age is 21.

not (Salary > 30000 or Age < 25)

Result: Logically false when Salary is 29,000 and Age is 21.

w = ( (let x = 5+3), (let y = 5-3), (let z = 5^3), 5.0/3.0 )

Values: x=8, y=2, z=75, w=1.7

See Also

Conventions

How To Construct Logic Expressions

How To Use Logic Expressions

OR

Performs a Boolean OR of two logic expressions.

Syntax

expression1 OR expression2

Parameters

expression1	A logic expression using conditional and Boolean operators. If the expression is complex, it must be enclosed in parentheses.
expression2	A logic expression using conditional and Boolean operators. If the expression is complex, it must be enclosed in parentheses.

Return Value

Logical, as follows:

Truth Table for Boolean OR		Expression1
Truth Table for Boolean OR		True	False
Expression2	True	True	True
Expression2	False	False	False

Example

The following expression is logically false only if Salary is 30,000 and Bonus is 0. In all other cases, the expression is logically true.

Salary <> 30000 or Bonus <> 0

See Also

About Boolean Expressions

About Conditional Expressions

XOR

Performs a Boolean XOR of two logic expressions.

Syntax

expression1 XOR expression2

Parameters

expression1	Any conditional expression or Boolean expression. If the expression is complex, it must be enclosed in parentheses.
expression2	Any conditional expression or Boolean expression. If the expression is complex, it must be enclosed in parentheses.

Return Value

Logical as follows:

Truth Table for Boolean XOR		Expression 1
Truth Table for Boolean XOR		True	False
Expression 2	True	False	True
Expression 2	False	True	False

Comments

Performs a Boolean XOR (exclusive OR) of two logic expressions.

Example

LastName = “Smith” xor FirstName = “John”

The entire expression is logically true only if LastName is Smith or FirstName is John, but not both; otherwise, the entire expression is logically false.

See Also

About Boolean Expressions

About Conditional Expressions

=, <, <=, <>, >, >= (Condition)

Compares two expressions and returns a value of “true” or “false”.

Syntax

expression1

=
<
<=
<>
>
>=

expression2

Parameters

expression1	any value expression
expression2	any value expression

Return Value

Logical

Comments

In a conditional expression, the less than sign (<) compares the expressions to its left and right, and is logically true if the expression on the left is “smaller” than the expression on the right; otherwise, it is logically false.

In a conditional expression, the less than or equals sign (<=) compares the expressions to its left and right, and is logically true if the expression on the left is “smaller” than or equal to the expression on the right; otherwise, it is logically false.

In a conditional expression, the not equals sign (<>) compares the expressions to its left and right, and is logically true if they are not equal; otherwise, it is logically false.

In a conditional expression, the equals sign (=) compares the expressions to its left and right, and is logically true if they are equal; otherwise, it is logically false.

In a conditional expression, the greater than sign (>) compares the expressions to its left and right, and is logically true if the expression on the left is “larger” than the expression on the right; otherwise, it is logically false.

In a conditional expression, the greater than or equals sign (>=) compares the expressions to its left and right, and is logically true if the expression on the left is “larger” than or equal to the expression on the right; otherwise, it is logically false.

Examples

case
when GeoLocation = "New York"
... commands ...
otherwise
... more commands ...
endcase

while var1 < 11
... commands ...
var1 = var1 + 1
endwhile

DayCare = {"subsidized" where GIncome <= 22000, "not subsidized"}

case
when GeoLocation <> "Madrid"
... commands ...
otherwise
... more commands ...
endcase

case
when GoodsValue > 2000
... commands ...
otherwise
... more commands ...
endcase

case
when Age >= 65
... commands ...
otherwise
... more commands ...
endcase

IS [NOT] [$]NULL

Checks a value to see if it is $Null.

Syntax

expression IS [NOT] $NULL

Parameters

expression

Any expression.

Return Value

Logical.

Comments

An IS $NULL comparison is logically true if expression is valueless (unassigned). If expression has been assigned any value (including the null string), then the comparison is logically false.

An IS NOT $NULL comparison is logically true if expression has been assigned any value (including the null string). If expression is valueless (unassigned), then the comparison is logically false.

$NULL can also be written as NULL.

Example

To find all employees whose records have no value recorded in the Age field, and then change that value to 39, enter

change all Employees where Age is $Null let Age = 39

See Also

About Boolean Expressions

About Conditional Expressions

WHERE

Controls the evaluation of other expressions.

Syntax

expression1 WHERE expression2

Parameters

expression1	A value expression.
expression2	A logic expression using conditional and Boolean operators.

Return Value

If expression2 is logically true, the value of expression1; otherwise, $Null.

Example

let i = { 1 where Age < 10,
2 where Age between 10 and 30,
4 where Age > 50, 3 }

Assigns a value to the variable i based on Age.

compute Employees evaluate
(let TotSal = $total(Salary where LastName = “Smith”)

Finds the total of the salaries of all employees named Smith.

See Also

About Boolean Expressions

About Conditional Expressions

Conventions

LET

Special Expression Formats

[NOT] LIKE

Matches an expression to a pattern.

Syntax

expression [NOT] LIKE pattern

Parameters

expression	An expression that evaluates to a character string.
pattern	An expression that evaluates to a character string. Pattern must consist of combinations of letters, digits, symbols, and the special wildcard characters % and _.

Return Value

Logical.

Comments

A LIKE comparison is logically true if expression matches patterns.

A NOT LIKE comparison is logically true if expression fails to match pattern.

Example

compute Employees where LastName like "_a%n"

Processes all records whose LastName values are three characters or more, the second character being an a, and the last character being an n.

find Parts where PartNo like "_ _\_%"

Finds all parts whose part numbers have an underscore as the third character.

find Parts where PartDesc like "%\\%"

Finds parts whose part description contains a backslash.

[NOT] IN

Compares one value to a list of values.

Syntax

expression [NOT] IN («expr»)

Parameters

expression	An expression that evaluates to either a number or a character string.
expr	A list of expressions whose values are to be compared to expression. Members of the list are separated from one another by commas.

Return Value

Logical

Comments

An IN comparison is logically true if expression is equal to at least one of the values in the specified list.

A NOT IN comparison is logically true if expression is not equal to any of the values in the specified list.

In either case, the comparison ends as soon as a logically true instance is found.

Example

The conditional expression that follows is logically true if the value of AirPollutants matches any of CFC, CO, or NOX.

AirPollutants in (" CFC","CO"," NOX")

The conditional expression that follows is logically true if the value obtained from either TicketAmt*5 or Receipts*10 equals 10,000.

10000 in ( TicketAmt * 5,Receipts * 10)

* (Multiply)

Multiplies one value by another.

Syntax

[expression1]*expression2

The asterisk (*) multiplies the expression on the left by the expression on the right.

Parameters

expression1	a number or expression that evaluates to a number
expression2	a number or expression that evaluates to a number

Comments

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

See Also

About Arithmetic Expressions

Rules of Precedence for Arithmetic Operators