how to pass the sqlx static check

[yxengine]

I want to transfer a row data between different methods. During the transfer process, a certain field value in the row data may be modified. However, the fields of the structure and the fields of the database are not in one-to-one correspondence. There are two methods at this time. practice

1. Define a new structure specifically for transfer and modification between methods. The data of the new structure is copied from row data.
2. Use the same structure, which can reduce one copy.

The 0.7.4 version of sqlx does not support the simultaneous use of sqlx::FromRow and sqlx::skip, which is related to the issue, so I want to add '' as colmn_name to the sql statement to set a default value for the non-existent field. Expectation The static check passes, but an error "required for Option<std::string::String> to implement Into<std::string::String>" will be prompted. The example is as follows

#[derive(Debug, sqlx::FromRow)]
pub struct Rule {
    pub rule_id: String,
    pub stat_name: String,
    pub stat_sql: String,
    pub period_name: String,
}

sqlx::query_as!(
            Rule,
            "SELECT rule_id, stat_name, '' as stat_sql, period_name FROM rule WHERE rule_id = $1 limit 1",
            rule_id
        )
        .fetch_one(conn)
        .await