Introduce generatedKey() on SqlResult

For PostgreSQL we can use RETURNING clause for fetching the generated keys, but in MySQL we can get the generated key via the last_insert_id in the OK_Packet OTTB, so we may add an interface for this in the sqlclient module for better usage.

[vietj]

I am worried that each database will have its peculiarities

Perhaps we can add notion of properties on SqlResult , to do something like result.property("lastInsertId") ?

we could also do the same using generics magic to avoid casting and expose constants with something like:

@VertxGen
interface SqlResultProperty<T> {
}

@VertxGen
interface SqlResult {
  ...
  <T> T property(SqlResultProperty<T> property);
  ...
}

@VertxGen
interface MySQLClient extends SqlClient {
  // Constant
   SqlResultProperty<Integer> LAST_INSERTED_ID = new SqlResultPropertyImpl<>();
}

[BillyYccc]

I agree we should avoid magic like injecting RETURNING clause into the SQL statement.

Since we use the same interface to represent the result as SqlResult, what I mean is adding a lastInsertId() method to the SqlResult interface.

• For MySQL we can return the id with the value from OK_Packet natively.
• For PostgreSQL we throw an UnsupportedOperation and give a hint to the users that they should write RETURNING SQL by themselves.