Database Management
Reference Manual
Expressions
Expressions
This section explains the PML 1 expressions package. These facilities are needed within AVEVA products, for example, to define report templates in AVEVA E3D™.
Note:
Generally, all these facilities are compatible with PML 2.
Expressions have types. For example, you can have numeric expressions, text expressions and logical expressions. All the elements in an expression must be of the correct type. For example, if you have a two numbers, x and y, and two text strings text1 and text2, the following expression is meaningless:
x + text1
$
However, both of the following expressions are valid:
x + y
$ adds the values of the numeric variables.
Text1 + text2
$ concatenates the two text strings.
Real expressions also have a physical dimension. This may be NONE when all values in the expression are purely numerical, but if any value has a physical dimension (such as being a length or mass) then all other values must be compatible with it and the result of the expression may have a physical dimension, or it may evaluate to a pure numerical value (1inch / 1mm = 25.4).
The following types of expressions are available:
•
Logical Expressions
•
Logical Array Expressions
•
Numeric (Real) Expressions
•
Numeric (Real) Functions
•
Text Expressions
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