Struct AddedColumnRisk 

pub struct AddedColumnRisk {
    pub null_without_default: bool,
    pub non_constant_default: bool,
    pub generated_stored: bool,
}

What an added column would do to rows that already exist.

SQLite refuses PRIMARY KEY and UNIQUE while it is still compiling, because no table can take them however empty it is. The other three it defers: a NOT NULL column with no default, a non-constant default and a STORED generated column are refused only when there is a row to break, and are accepted on an empty table. That is not a quirk worth smoothing over - it is the difference between a migration that runs on a fresh database and one that runs on a populated one - so the binder records what it saw and the executor, which knows the row count, decides.

Fields

null_without_default: bool

NOT NULL with nothing to fill the existing rows with.

non_constant_default: bool

A DEFAULT the existing rows cannot all be given one answer from.

generated_stored: bool

GENERATED ALWAYS AS (...) STORED, which needs a value in every record.

Implementations

impl AddedColumnRisk

pub fn refusal(&self) -> Option<&'static str>

Returns the refusal a table with rows in it owes, in SQLite’s wording.

The capitalisation is the reference’s own and is inconsistent between the three; it is reproduced rather than tidied, because a caller matching on the message is matching on what SQLite prints.

Trait Implementations

impl Clone for AddedColumnRisk

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for AddedColumnRisk

impl Debug for AddedColumnRisk

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for AddedColumnRisk

fn default() -> Self

Returns the “default value” for a type.

impl Eq for AddedColumnRisk

impl PartialEq for AddedColumnRisk

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for AddedColumnRisk