The CONNECT BY clause determines the parent-child relationship of rows when performing a hierarchical query. The syntax of the CONNECT BY clause is as follows:

CONNECT BY { PRIOR parent_expr = child_expr |
 child_expr = PRIOR parent_expr }

parent_expr is evaluated on a candidate parent row. If parent_expr = child_expr results in TRUE for a row returned by the FROM clause, this row is considered a child of the parent.

The following optional clauses can be specified in conjunction with the CONNECT BY clause:

START WITH start_expression

The rows returned by the FROM clause on which start_expression evaluates to TRUE become the root nodes of the hierarchy.

ORDER SIBLINGS BY expression [ ASC | DESC ] [, ...]

Sibling rows of the hierarchy are ordered by expression in the result set.

Note PolarDB database compatible with Oracle does not support the use of AND or other operators in the CONNECT BY clause.