分析函式學習2 SYS_CONNECT_BY_PATH

SYS_CONNECT_BY_PATH is valid only in hierarchical queries. It returns the path of a column value from root to node, with column values separated by char for each row returned by CONNECT BY condition.
Both column and char can be any of the datatypes CHAR, VARCHAR2, NCHAR, or NVARCHAR2. The string returned is of VARCHAR2 datatype and is in the same character set as column.

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The following example returns the path of employee names from employee Kochhar to all employees of Kochhar (and their employees):

SELECT LPAD(' ', 2*level-1)||SYS_CONNECT_BY_PATH(last_name, '/') "Path"
FROM employees
START WITH last_name = 'Kochhar'
CONNECT BY PRIOR employee_id = manager_id;
Path
---------------------------------------------------------------
/Kochhar
/Kochhar/Greenberg
/Kochhar/Greenberg/Faviet
/Kochhar/Greenberg/Chen
/Kochhar/Greenberg/Sciarra
/Kochhar/Greenberg/Urman
/Kochhar/Greenberg/Popp
/Kochhar/Whalen
/Kochhar/Marvis
/Kochhar/Baer
/Kochhar/Higgens
/Kochhar/Higgens/Gietz
12 rows selected.