Though R is not strictly OO it is sometimes useful to add some object orientation.
In the case of a shiny app with an dynamically created user interface a bit
of pseudo polymorphism helps to avoid too many but,ifs and elses.
Depending on the query type that is selected by the user a UI creation
method is called.
Usage
createUI(x, con, ...)
## S3 method for class 'key'
createUI(x, con, ...)
## S3 method for class 'set'
createUI(x, con, ...)
## S3 method for class 'md'
createUI(x, con, ...)
Arguments
x
character query type.
con
PostgreSQL Connection object.
...
additional arguments to be passed to the respective methods.
providing 
.