dbautojoinr: Automatic Joining of SQL Tables

Creates the SQL Connection and creates/Reads the db_fields .csv file according to the db_fields standard and according to what the SQL database looks like

initialise_return_db_fields(
  csv_path,
  Driver,
  Database,
  Server,
  UID,
  PWD,
  Trusted_Connection,
  Port = 1433,
  ...,
  ForceCreate_csv = FALSE,
  ExcludeIdentities = FALSE,
  ExcludeForeignKeys = TRUE,
  Update_DBEnv_DBFields = FALSE,
  ExcludeAuditingFields = FALSE,
  ExcludeSYSDIAGRAMS = TRUE,
  RegexToSelectTables = "^(DIM_|FACT_|TBL_)",
  UpdateDBFieldsFromDBCon = FALSE,
  DefaultToExclude = FALSE
)

`csv_path`	A String. The path of the db_fields .csv file to read (or to be created if it doesn't exist)
`Driver`	A string. A SQL Driver, etc.: SQL Server;
`Database`	A string. The name of the SQL Database itself
`Server`	A string. A name that resolves into the SQL Machine, or the IP to the SQL Machine
`UID`	A string. The Username credential for the SQL Connection. NULL if Windows Login is to be used
`PWD`	A string. The Password credential for the SQL Connection. NULL if Windows Login is to be used
`Trusted_Connection`	A Boolean. TRUE or FALSE on whether Windows Login is to be used, if a string is used it'll be passed as is.
`Port`	An Integer. The Port which the SQL Listener is listening at
`...`	If the relationships exist on the SQL Database, this can be left blank. Logical expressions for the SQL Relationships in the format: table1$FKcolumn1 == table2$IDcolumn5, table1$FKcolumn2 == table3$IDcolumn5, ...
`ForceCreate_csv`	A Boolean. If TRUE then even if the db_fields exist, it will be deleted and overwriten by a newly created default db_fields
`ExcludeIdentities`	A Boolean. The default inclusion behaviour for SQL Table Identities. If we're going to perform more joins afterwards or if we need to have a reference as to which table each column belongs to, then we shouldn't exclude them; if we only care about extrapolating information from each specific row, then we can exclude them by default and edit to include just the row identifier ID.
`ExcludeForeignKeys`	A Boolean. If we need to perform manual joins afterwards or keep a reference as to with which table there's a connection, then we need them; otherwise we can safely exclude them
`Update_DBEnv_DBFields`	A Boolean. If set to TRUE, you can have an internal main db_fields accessible via db$db_fields usually acting as the main db_fields. Default is FALSE as having local db_fields variables is the default behaviour.
`UpdateDBFieldsFromDBCon`	A Boolean. If set to TRUE, then the db_fields saved on the file will be updated to reflect any changes in the SQL Database (removal or addition of Columns and Tables). User options are kept.
`DefaultToExclude`	A Boolean. If TRUE, every non-ID and non-FK column will default to Include == FALSE, unless ExcludeIdentities or ExcludeForeignKeys is set to TRUE
`ExcludeAuditingFields.`	A Boolean. If TRUE, any SQL Columns ending with "_OrigEntryOn", "_OrigEntryBy", "_EntryOn", "_EntryBy", "_CompName", "_Remote" or "_Username" will have INCLUDE == FALSE by default
`ExcludeSYSDIAGRAMS.`	A Boolean. If TRUE, any SQL Columns on the table "sysdiagrams" will have INCLUDE == FALSE by default
`RegexToSelectTables.`	A String. It defaults to getting all SQL Tables whose name begins with DIM_, FACT_, or TBL_.

db_fields <- initialise_return_db_fields(csv_path = "db_fields.csv",
                                         ForceCreate_csv = FALSE,
                                         ExcludeIdentities = FALSE,
                                         ExcludeForeignKeys = TRUE,
                                         Driver = "{SQL Server};",
                                         Database = "MyDatabaseName",
                                         Server = "123.456.7.8",
                                         UID = NULL,
                                         PWD = NULL,
                                         Trusted_Connection = TRUE,
                                         Port = 1433,
                                         table1$FKcolumn2 == table2$IDcolumn1,
                                         table1$FKcolumn3 == table3$IDcolumn1
                                         )