Method alias_if_changed

datafusion/expr/src/expr.rs:1776–1783

Ensure `expr` has the name as `original_name` by adding an alias if necessary.

(self, original_name: String)

    /// Ensure `expr` has the name as `original_name` by adding an
    /// alias if necessary.
    pub fn alias_if_changed(self, original_name: String) -> Result<Expr> {
        let new_name = self.name_for_alias()?;
        if new_name == original_name {
            return Ok(self);
        }

        Ok(self.alias(original_name))
    }

    /// Return `self AS name` alias expression
    pub fn alias(self, name: impl Into<String>) -> Expr {