append_to_temp_table: Appends rows to a temporary table
In rOpenHealth/rEHR: Manipulating and Analysing Electronic Health Record Data

This function checks if a table is a temp table and then adds to it based on the select statement The check is to maintain the integrity of the database

1	append_to_temp_table(db, tab_name, columns, select_query)

`db`	a database connection
`tab_name`	the name of the temporary table being appended to
`columns`	character vector of columns in tab_name
`select_query`	SQL query for the selector