Merge SQL Queries to One Query That Performs a Full Left Join

Usage

sqlFullLeftJoin(sqls, key)

Arguments

sqls: list of SQL queries each of which is expected to contain an attribute alias giving the alias name for the query
key: name of the primary key field, being selected in each SQL query contained in sqls

Value

vector of character of length one representing the result of "left join"-ing all sub-queries given in sqls

Examples

sql <- sqlFullLeftJoin(key = "id", list(
  structure("SELECT id, field_1 from table_1", alias = "t1"),
  structure("SELECT id, field_2, field_3 from table_2", alias = "t2"),
  structure("SELECT id, field_4 from table_3", alias = "t3")
))

cat(sql)
#> ( SELECT id, field_1 from table_1 AS t1 
#>  LEFT JOIN SELECT id, field_2, field_3 from table_2 AS t2 
#>  ON ( t1.id = t2.id ) )  
#>  LEFT JOIN SELECT id, field_4 from table_3 AS t3 
#>  ON ( t1.id = t3.id )