31.1.6 Using Strings

Enclose string values within double quotation marks in the Expression or the Thresholds text boxes. For example, the expression for the Slave I/O Thread Not Running advisor is:

(%Slave_running% == "ON") && (%Slave_IO_Running% != THRESHOLD)

Similarly, the Critical Alerts threshold text box is set to a value of "Yes".

When the expression is evaluated, either "OFF" or "ON" is substituted for %Slave_running%, and "Yes" or "No" for %Slave_IO_Running%, depending on the state of your system. If the slave is running but the I/O thread is not, the expression becomes:

("ON" == "ON") && ("No" != "Yes")

Without quotation marks, this expression would not evaluate to TRUE as it should.


So that it is interpreted properly, the == operator is converted to = before being passed to the MySQL expression parser.