CTE-based sequence generation using HSQLDB

Question

I use a recursive generic table expression to retrieve a sequence of sequence number. The following query works with Postgres, SQL Server and H2 (minus part VALUES).

WITH RECURSIVE t(n, level_num) AS (
    SELECT next value for seq_parent_id as n,
           1 as level_num
      FROM (VALUES(0))

    UNION ALL

    SELECT next value for seq_parent_id as n,
           level_num + 1 as level_num
      FROM t
     WHERE level_num < ?)
SELECT n FROM t

However, with HSQLDB 2.4.0 I get the following exception

java.sql.SQLSyntaxErrorException: user lacks privilege or object not found: T
    at org.hsqldb.jdbc.JDBCUtil.sqlException(Unknown Source)
    at org.hsqldb.jdbc.JDBCUtil.sqlException(Unknown Source)
    at org.hsqldb.jdbc.JDBCStatement.fetchResult(Unknown Source)
    at org.hsqldb.jdbc.JDBCStatement.executeQuery(Unknown Source)
    ... 
Caused by: org.hsqldb.HsqlException: user lacks privilege or object not found: T
    at org.hsqldb.error.Error.error(Unknown Source)
    at org.hsqldb.error.Error.error(Unknown Source)
    at org.hsqldb.ParserDQL.readTableName(Unknown Source)
    at org.hsqldb.ParserDQL.readTableOrSubquery(Unknown Source)
    at org.hsqldb.ParserDQL.XreadTableReference(Unknown Source)
    at org.hsqldb.ParserDQL.XreadFromClause(Unknown Source)
    at org.hsqldb.ParserDQL.XreadTableExpression(Unknown Source)
    at org.hsqldb.ParserDQL.XreadQuerySpecification(Unknown Source)
    at org.hsqldb.ParserDQL.XreadSimpleTable(Unknown Source)
    at org.hsqldb.ParserDQL.XreadQueryPrimary(Unknown Source)
    at org.hsqldb.ParserDQL.XreadQueryTerm(Unknown Source)
    at org.hsqldb.ParserDQL.XreadSetOperation(Unknown Source)
    at org.hsqldb.ParserDQL.XreadQueryExpressionBody(Unknown Source)
    at org.hsqldb.ParserDQL.XreadQueryExpression(Unknown Source)
    at org.hsqldb.ParserDQL.XreadSubqueryTableBody(Unknown Source)
    at org.hsqldb.ParserDQL.XreadTableNamedSubqueryBody(Unknown Source)
    at org.hsqldb.ParserDQL.XreadQueryExpression(Unknown Source)
    at org.hsqldb.ParserDQL.compileCursorSpecification(Unknown Source)
    at org.hsqldb.ParserCommand.compilePart(Unknown Source)
    at org.hsqldb.ParserCommand.compileStatements(Unknown Source)
    at org.hsqldb.Session.executeDirectStatement(Unknown Source)
    at org.hsqldb.Session.execute(Unknown Source)
    ... 37 more

This particular use case can also be resolved with a combination of UNNESTand SEQUENCE_ARRAY, but I would like to avoid having to enter a specific HSQLDB code path.

Answer 1

, .

:

WITH RECURSIVE
t(level_num)
AS
(
    VALUES(1)

    UNION ALL

    SELECT
        level_num + 1
    FROM t
    WHERE level_num < 10
)
SELECT level_num 
FROM t
;

, :

HyperSQL 265 . , .

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---

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