Enum AlterColumnOperation 

pub enum AlterColumnOperation {
    SetType {
        data_type: DbType,
    },
    SetMaxLength {
        max_length: i32,
    },
    DropMaxLength,
}

Representation of a single change to an existing column.

Each variant renders into exactly one ALTER TABLE statement, or into none at all in sqlite: it has no ALTER COLUMN, and none of these changes are observable in a STRICT table - DbType::VarChar and DbType::Text are both TEXT, every integer is INTEGER, both floats are REAL, and a maximum length is never enforced.

Variants

SetType

Set the column’s type

The type has to be one which is fully described by itself. A DbType::VarChar carries its maximum length and a DbType::Choices its enum, so neither can be rendered from the type alone.

Fields

data_type: DbType

The type to change the column to

SetMaxLength

Add the check constraint enforcing the column’s maximum length

A column which already has one has to drop it first: a constraint can’t be redefined, only replaced.

Fields

max_length: i32

The maximum number of characters the column may hold

DropMaxLength

Drop the check constraint enforcing the column’s maximum length

Trait Implementations

impl Clone for AlterColumnOperation

fn clone(&self) -> AlterColumnOperation

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for AlterColumnOperation

impl Debug for AlterColumnOperation

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

Formats the value using the given formatter.