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LEVEL
Supported by ✅ Open Source Edition ✅ Express Edition ✅ Professional Edition ✅ Enterprise Edition
The LEVEL pseudo column allows for accessing the hierarchy level of the current row, or in other words, the depth of the current row in the hierarchy's tree.
SELECT
child,
parent,
sys_connect_by_path(child, '/'),
level
FROM (
VALUES
(1, null),
(2, 1),
(3, 2),
(4, 1)
) AS t (child, parent)
START WITH
parent IS NULL
CONNECT BY NOCYCLE
PRIOR child = parent;
Field<Integer> child = field("child", INTEGER);
Field<Integer> parent = field("parent", INTEGER);
ctx.select(
child,
parent,
sysConnectByPath(child, "/"),
level())
.from(values(
row(val(1), val(null, INTEGER)),
row(2, 1),
row(3, 2),
row(4, 1)).as(table("t"), child, parent))
.startWith(parent.isNull())
.connectByNoCycle(prior(child).eq(parent))
.fetch();
The result being, for example
+-------+--------+---------------------+-------+
| child | parent | sys_connect_by_path | level |
+-------+--------+---------------------+-------+
| 1 | {null} | /1 | 1 |
| 2 | 1 | /1/2 | 2 |
| 3 | 2 | /1/2/3 | 3 |
| 4 | 1 | /1/4 | 2 |
+-------+--------+---------------------+-------+
Dialect support
This example using jOOQ:
level()
Translates to the following dialect specific expressions:
Aurora Postgres, CockroachDB, DB2, Exasol, Firebird, H2, HSQLDB, Informix, MariaDB, MySQL, Oracle, Postgres, Redshift, SQLDataWarehouse, SQLServer, SQLite, Snowflake, Sybase, Teradata, Trino, YugabyteDB
level
ASE, Access, Aurora MySQL, BigQuery, ClickHouse, Databricks, DuckDB, Hana, MemSQL, Spanner, Vertica
/* UNSUPPORTED */
Generated with jOOQ 3.21. Support in older jOOQ versions may differ. Translate your own SQL on our website
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