PostgreSQL supports left unary,
right unary, and binary operators. Operators can be overloaded;
that is, the same operator name can be used for different operators
that have different numbers and types of operands. When a query
is executed, the system determines the operator to call from
the number and types of the provided operands.
Create a Operator
To create a operator:
Select the Database in the Tree View and select Others
>
Operator from the toolbar
Press the
New Operator button
Enter Operator properties and fields on the appropriate
tabs of the New Operator Editor
Click OK
Design a Operator
To design a operator:
Select the Database in the Tree View and select Others
>
Operator from the toolbar
Select the operator you want to design.
Press the
Design Operator button.
Edit Operator properties and fields on the appropriate
tabs of the Design Operator Editor
Click OK
Delete a Operator
To delete a operator:
Select the Database in the Tree View and select Others
>
Operator from the toolbar
Operator from the toolbar
New Operator button 
Design Operator button. 
Delete Operator button. 
