Method preferred_type

src/sql/src/func.rs:195–214

Extracted from PostgreSQL 9.6. ```ignore SELECT typcategory, typname, typispreferred FROM pg_catalog.pg_type WHERE typispreferred = true ORDER BY typcategory; ```

(&self)

    /// ORDER BY typcategory;
    /// ```
    pub fn preferred_type(&self) -> Option<SqlScalarType> {
        match self {
            Self::Array
            | Self::BitString
            | Self::Composite
            | Self::Enum
            | Self::Geometric
            | Self::List
            | Self::NetworkAddress
            | Self::Pseudo
            | Self::Range
            | Self::Unknown
            | Self::UserDefined => None,
            Self::Boolean => Some(SqlScalarType::Bool),
            Self::DateTime => Some(SqlScalarType::TimestampTz { precision: None }),
            Self::Numeric => Some(SqlScalarType::Float64),
            Self::String => Some(SqlScalarType::String),
            Self::Timespan => Some(SqlScalarType::Interval),
        }
    }
}

/// Builds an expression that evaluates a scalar function on the provided