Function char_length 

pub fn char_length<'a, V, E>(
    expr: E,
) -> SQLExpr<'a, V, <E::SQLType as LengthPolicy<V::DialectMarker>>::Output, E::Nullable, E::Aggregate, E::Sources>
where
    V: SQLParam + 'a,
    E: Expr<'a, V>,
    E::SQLType: LengthPolicy<V::DialectMarker>,

Number of characters in a text value.

Renders CHAR_LENGTH(expr) on PostgreSQL and MySQL and LENGTH(expr) on SQLite, which counts characters. The argument must be text. The result is an integer (see LengthPolicy) and keeps the argument’s nullability.

Examples

// SQLite
assert_eq!(char_length(users.name).sql(), r#"LENGTH ("users"."name")"#);