Create nicer SQL

[mgirlich]

The SQL queries generated by dbplyr are not very readable. Of course one can use one of the many available online SQL formatters but it would be still be very nice if the query itself would be more readable.

For example turn this

SELECT `x.x`, `x.y`, `y`
FROM (SELECT `x.x`, `x.y`, `y`, AVG(`x.x`) OVER (PARTITION BY `y`) AS `q01`
FROM (SELECT `LHS`.`x` AS `x.x`, `RHS`.`x` AS `x.y`, `y`
FROM `dbplyr_001` AS `LHS`
LEFT JOIN `dbplyr_002` AS `RHS`
ON (LHS.x < RHS.x)
))
WHERE (`q01` > 1.0)

into something like this

SELECT `x.x`,
       `x.y`,
       `y`
FROM
  (SELECT `x.x`,
          `x.y`,
          `y`,
          AVG(`x.x`) OVER (PARTITION BY `y`) AS `q01`
   FROM
     (SELECT `LHS`.`x` AS `x.x`,
             `RHS`.`x` AS `x.y`,
             `y`
      FROM `dbplyr_001` AS `LHS`
      LEFT JOIN `dbplyr_002` AS `RHS` ON (LHS.x < RHS.x)))
WHERE (`q01` > 1.0)

I looked around a little for existing R packages providing an SQL formatter but there seems to hardly any. I found sqlparseR which has quite a lot of extra Python dependencies.

dbplyr could directly generate pretty SQL code but this would probably require quite a bit of work and maintenance. So, it might be easier to create a wrapper around an existing SQL formatter.