Function left 

pub fn left<'a, V, E, N>(
    expr: E,
    n: N,
) -> SQLExpr<'a, V, <V::DialectMarker as DialectTypes>::Text, <E::Nullable as Nullability>::Or<N::Nullable>, <E::Aggregate as AggregateKind>::Or<N::Aggregate>, (E::Sources, N::Sources)>
where
    V: SQLParam + 'a,
    V::DialectMarker: DialectSupports<LeftRight>,
    E: Expr<'a, V>,
    E::SQLType: Textual,
    N: Expr<'a, V>,
    N::SQLType: Integral,
    N::Nullable: Nullability,
    N::Aggregate: AggregateKind,

The first n characters of a text value (LEFT), on PostgreSQL and MySQL.

expr must be text and n an integer. The result is text, nullable if either argument is. SQLite has no LEFT; use substr there.

Examples

assert_eq!(left(users.name, 3).sql(), r#"LEFT ("users"."name", $1)"#);