Order of operations in queries (precedence rules)
The information in this topic is for advanced users who understand precedence in programming languages. In the Query Builder, the order in which operations occur can determine which virtual machines are selected and backed up.
The following table lists the order of operations, or precedence, from highest to lowest (7 is the highest). For example, an operation with a precedence of 6 (such as Contains) is evaluated before an operation with a precedence of 5 (such as Greater).
Table: Order of operations
Operation | Description | Precedence |
|---|---|---|
!x | Produces the value 0 if x is true (nonzero) and the value 1 if x is false (0). | 7 |
x Contains y | Does y exist somewhere in x | 6 |
x StartsWith y | Does x start with y | 6 |
x EndsWith y | Does x end with y | 6 |
x AnyOf list | Does x appear in list | 6 |
x Greater y | Is x greater than y | 5 |
x GreaterEqual y | Is x greater than or equal to y | 5 |
x Less y | Is x less than y | 5 |
x LessEqual y | Is x less than or equal to y | 5 |
x Equal y | Is x equal to y | 4 |
x NotEqual y | Is x not equal to y | 4 |
Not x | operator produces the value 0 if x is true (nonzero) and the value 1 if x is false (0). | 3 |
x And y | True if both x and y are true | 2 |
x OR y | True if either x or y are true | 1 |
Note the following:
AND has a higher precedence than OR.
In the Query Builder's Advanced Mode, you can use parentheses to change the order of evaluation in the rules that use AND or OR.
In the Query Builder's Advanced Mode, you can combine two or more operations in a single rule without AND or OR to join them. Precedence determines the order in which the operations are evaluated within the rule.
Example of a rule that includes three operations:
Displayname StartsWith "L" NotEqual Displayname contains "x"
This rule selects the following virtual machines:
Virtual machines with the names that start with L but do not contain x.
Virtual machines with the names that do not start with L but that do contain x.
Explanation: The StartsWith and Contains operations have a precedence of 6, whereas NotEqual has a lower precedence of 3. Starting on the left, the StartsWith operation is evaluated first and the Contains operation is evaluated next. The last operation to be evaluated is Not Equal.
See Use Advanced mode to create a query for virtual machine selection.