Function string_agg 

pub fn string_agg<'a, V, E, D>(
    expr: E,
    delimiter: D,
) -> SQLExpr<'a, V, <V::DialectMarker as DialectTypes>::Text, Null, Agg, (E::Sources, D::Sources)>
where
    V: SQLParam + 'a,
    V::DialectMarker: DialectSupports<PostgresAggregate>,
    E: Expr<'a, V>,
    E::SQLType: Textual,
    D: Expr<'a, V>,
    D::SQLType: Textual,

Joins text values with a delimiter (STRING_AGG), on PostgreSQL.

Both arguments must be text. The result is text, nullable, and an aggregate. On SQLite and MySQL, use group_concat.

Examples

let names = string_agg(users.name, ", ");
assert_eq!(names.sql(), r#"STRING_AGG ("users"."name", $1)"#);