pub struct CaseStatement {
    pub case_token: AttachedToken,
    pub match_expr: Option<Expr>,
    pub when_blocks: Vec<ConditionalStatementBlock>,
    pub else_block: Option<ConditionalStatementBlock>,
    pub end_case_token: AttachedToken,
}

CASE
    WHEN EXISTS(SELECT 1)
        THEN SELECT 1 FROM T;
    WHEN EXISTS(SELECT 2)
        THEN SELECT 1 FROM U;
    ELSE
        SELECT 1 FROM V;
END CASE;

The CASE token that starts the statement.

Optional expression to match against in CASE ... WHEN.

The WHEN ... THEN blocks of the CASE statement.

Optional ELSE block for the CASE statement.

The last token of the statement (END or CASE).