Function isIntrospectionQuery

src/db/utils.ts:214–260

* Identify queries that expose schema/column metadata. Combines a textual * pre-screen (catches statements the parser doesn't understand, like * `SHOW FULL COLUMNS FROM users`) with an AST walk (catches `db.table` * references to `information_schema` or `mysql` anywhere in the query, * including

(sql: string)

 * downstream executor will reject or surface the parse error normally.
 */
function isIntrospectionQuery(sql: string): IntrospectionResult {
  const showMatch = sql.match(SHOW_INTROSPECTION_RE);
  if (showMatch) {
    const keyword = showMatch[1].toUpperCase().replace(/\s+/g, " ");
    if (keyword.startsWith("COLUMNS") || keyword.startsWith("FIELDS")) {
      return { kind: "show_columns" };
    }
    if (keyword.startsWith("CREATE")) {
      return { kind: "show_create" };
    }
    if (
      keyword.startsWith("INDEX") ||
      keyword.startsWith("KEYS")
    ) {
      return { kind: "show_index" };
    }
    // Table-/database-level listings: schema topology only, no column data.
    if (
      keyword === "TABLES" ||
      keyword.startsWith("TABLE STATUS") ||
      keyword === "DATABASES" ||
      keyword === "SCHEMAS" ||
      keyword.startsWith("CHARACTER") ||
      keyword === "CHARSET" ||
      keyword === "COLLATION"
    ) {
      return { kind: "show_passthrough" };
    }
    return { kind: "show_other" };
  }
  if (DESCRIBE_RE.test(sql) || EXPLAIN_TABLE_RE.test(sql)) {
    return { kind: "describe" };
  }

  let astOrArray: AST | AST[];
  try {
    astOrArray = parser.astify(sql, { database: "mysql" });
  } catch {
    return { kind: null };
  }
  const statements = Array.isArray(astOrArray) ? astOrArray : [astOrArray];
  for (const stmt of statements) {
    const kind = findIntrospectionKind(stmt);
    if (kind) return { kind };
  }
  return { kind: null };
}

function findIntrospectionKind(node: unknown): IntrospectionKind | null {
  if (node == null || typeof node !== "object") return null;