String Interpolation: SQL revisited: Dynamic Table Names

[Steven Schveighoffer]

On Friday, 23 February 2024 at 23:47:47 UTC, kdevel wrote:
> After the DIP 1036(e) discussions I am under the impression 
> that with the upcoming dmd release one shall be entitled to 
> instead
>
>     auto result = db.rows ("select id, a from b where id = ?", 
> id);
>
> write
>
>     auto result = db.rows (i"select id, a from b where id = 
> $id");
>
> But what shall be written if the table from which the data are 
> selected is variable, too? E.g.
>
>     string t = "ta-ble";
>     :
>     auto result
>        = db.rows ("select id, a from `" ~ t ~ "` where id = ?", 
> id);
>
> What if the escaping rules for table names and data are 
> different? Can query authors benefit from string interpolation 
> in this case?

This could be up to the db library to deal with. It would have to 
know the context of the interpolation to know whether to just 
straight-replace with the given string, or to use a prepared 
statement. My suggestion would be for the library to either have 
a specialized syntax, or a specialized type that it considers to 
be a part of the query that is runtime-decided-sql.

e.g.:

```d
RuntimeSql rsql(string data) { return RuntimeSql(data); }

...
auto result = db.rows(i"select id, a from $(t.rsql) where id = 
$(id)");
```

-Steve