Check SQL queries at compile time

[Luflosi]

It would be nice to verify the queries at compile time.
However I found this to have too many papercuts for my taste.
Here are my reasons for not verifying the queries at compile-time with SQLx:

• Can't indent the SQL queries nicely using the indoc! macro
• The database needs to already exist while compiling, requiring extra steps
• SQLx doesn't know that INTEGER PRIMARY KEY always implies NOT NULL so the inferred datatype is <Option<i64> instead of i64. This could be worked around by explicitly adding NOT NULL but I don't want to add meaningless code
• The following code does not compile because two parameters are expected while I think only one should be required:

  let _ = sqlx::query!("
  INSERT OR IGNORE INTO zones (name) VALUES (?1);
  SELECT id FROM zones WHERE name = ?1;
  ", zone).fetch_one(conn).await?;

If at least two of these issues can be resolved, I'd be willing to implement this.