Identify table references in the projections

[kasvith]

Hello,

The following query produces the AST listed below

Code

    fn test_process_sql_statements() {
        let query = "SELECT country.country from country;";
        let ast = Parser::parse_sql(&sqlparser::dialect::MySqlDialect {}, query).unwrap();
        println!("{:?}", ast);
    }

AST

[Query(Query {
    with: None,
    body: Select(Select {
        distinct: None,
        top: None,
        top_before_distinct: false,
        projection: [
            UnnamedExpr(CompoundIdentifier([
                Ident {
                    value: "country",
                    quote_style: None,
                },
                Ident {
                    value: "country",
                    quote_style: None,
                },
            ])),
        ],
        into: None,
        from: [
            TableWithJoins {
                relation: Table {
                    name: ObjectName([
                        Ident {
                            value: "country",
                            quote_style: None,
                        },
                    ]),
                    alias: None,
                    args: None,
                    with_hints: [],
                    version: None,
                    with_ordinality: false,
                    partitions: [],
                },
                joins: [],
            },
        ],
        lateral_views: [],
        prewhere: None,
        selection: None,
        group_by: Expressions([], []),
        cluster_by: [],
        distribute_by: [],
        sort_by: [],
        having: None,
        named_window: [],
        qualify: None,
        window_before_qualify: false,
        value_table_mode: None,
        connect_by: None,
    }),
    order_by: None,
    limit: None,
    limit_by: [],
    offset: None,
    fetch: None,
    locks: [],
    for_clause: None,
    settings: None,
    format_clause: None,
})]

Now imagine we want to identify the table name in a projection, with the CompoundIdentifier vec whats the best possible way to do it?

Can we assume the first element of vector is always the table name? whats a possible scenario where compound idents can have more than 2 elements?

[kasvith]

Ok as per docs https://docs.rs/sqlparser/0.52.0/sqlparser/ast/enum.Expr.html#variant.CompoundIdentifier

if the vec has 2 elements it looks like parser is evaluating it to table_alias.col and if its 3 elements its schema.table.col