Troubles compiling the given example select query

[d3v3lop3rDE]

I can't compile your example with these errors:

error[E0277]: the ? operator can only be used in a function that returns Result or Option (or another type that implements Try)
--> src\main.rs:7:16
|
4 | / fn main() {
5 | |
6 | | // Connect to a database.
7 | | let conn = Connection::connect("scott", "tiger", "//localhost/XE")?;
| | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot use the ? operator in a function that returns ()
... |
29 | | }
30 | | }
| |_- this function should return Result or Option to accept ?
|
= help: the trait Try is not implemented for ()
= note: required by from_error

error[E0277]: the ? operator can only be used in a function that returns Result or Option (or another type that implements Try)
--> src\main.rs:13:16
|
4 | / fn main() {
5 | |
6 | | // Connect to a database.
7 | | let conn = Connection::connect("scott", "tiger", "//localhost/XE")?;
... |
13 | | let rows = conn.query(sql, &[&30])?;
| | ^^^^^^^^^^^^^^^^^^^^^^^^ cannot use the ? operator in a function that returns ()
... |
29 | | }
30 | | }
| |_- this function should return Result or Option to accept ?
|
= help: the trait Try is not implemented for ()
= note: required by from_error

error[E0277]: the ? operator can only be used in a function that returns Result or Option (or another type that implements Try)
--> src\main.rs:15:19
|
4 | / fn main() {
5 | |
6 | | // Connect to a database.
7 | | let conn = Connection::connect("scott", "tiger", "//localhost/XE")?;
... |
15 | | let row = row_result?;
| | ^^^^^^^^^^^ cannot use the ? operator in a function that returns ()
... |
29 | | }
30 | | }
| |_- this function should return Result or Option to accept ?
|
= help: the trait Try is not implemented for ()
= note: required by from_error

error[E0277]: the ? operator can only be used in a function that returns Result or Option (or another type that implements Try)
--> src\main.rs:17:29
|
4 | / fn main() {
5 | |
6 | | // Connect to a database.
7 | | let conn = Connection::connect("scott", "tiger", "//localhost/XE")?;
... |
17 | | let ename: String = row.get(0)?;
| | ^^^^^^^^^^^ cannot use the ? operator in a function that returns ()
... |
29 | | }
30 | | }
| |_- this function should return Result or Option to accept ?
|
= help: the trait Try is not implemented for ()
= note: required by from_error

error[E0277]: the ? operator can only be used in a function that returns Result or Option (or another type that implements Try)
--> src\main.rs:19:24
|
4 | / fn main() {
5 | |
6 | | // Connect to a database.
7 | | let conn = Connection::connect("scott", "tiger", "//localhost/XE")?;
... |
19 | | let sal: i32 = row.get("sal")?;
| | ^^^^^^^^^^^^^^^ cannot use the ? operator in a function that returns ()
... |
29 | | }
30 | | }
| |_- this function should return Result or Option to accept ?
|
= help: the trait Try is not implemented for ()
= note: required by from_error

error[E0277]: the ? operator can only be used in a function that returns Result or Option (or another type that implements Try)
--> src\main.rs:23:33
|
4 | / fn main() {
5 | |
6 | | // Connect to a database.
7 | | let conn = Connection::connect("scott", "tiger", "//localhost/XE")?;
... |
23 | | let comm: Option = row.get(2)?;
| | ^^^^^^^^^^^ cannot use the ? operator in a function that returns ()
... |
29 | | }
30 | | }
| |_- this function should return Result or Option to accept ?
|
= help: the trait Try is not implemented for ()
= note: required by from_error

error: aborting due to 6 previous errors; 1 warning emitted

I am using Rust 1.52.1

[kubo]

You need to learn error handling. Especially this section.

[kubo]

Examples use ? to follow this API guideline.

[d3v3lop3rDE]

Thank you! 🙈