如何在 HSQLDB 中查找顺序编号中的空白？

Question

我正在努力使 this answer made for MySQL 适应 HSQLDB（2.4.0，通过 Hibernate 5.2.12）。我已将 MySQL "IF" 函数替换为 "CASE WHEN" 调用，如下所示：

SELECT
 CONCAT(z.expected, CASE WHEN z.got-1>z.expected THEN CONCAT(' thru ',z.got-1) ELSE '' END) AS missing
FROM (
 SELECT
  @rownum\:=@rownum+1 AS expected,
  CASE WHEN @rownum=id THEN 0 ELSE @rownum\:=id END AS got
 FROM
  (SELECT @rownum\:=0) AS a
  JOIN Notices
  WHERE fonds_cote = '1Fi'
  ORDER BY id
 ) AS z
WHERE z.got!=0;

: 被转义以避免 Hibernate 的解析错误。仍然，它不起作用，我面临：

org.hsqldb.HsqlException: unexpected token: (
    at org.hsqldb.error.Error.parseError(Unknown Source) ~[hsqldb-2.4.0.jar:2.4.0]
    at org.hsqldb.ParserBase.unexpectedToken(Unknown Source) ~[hsqldb-2.4.0.jar:2.4.0]
    at org.hsqldb.ParserDQL.XreadSelect(Unknown Source) ~[hsqldb-2.4.0.jar:2.4.0]
    at org.hsqldb.ParserDQL.XreadQuerySpecification(Unknown Source) ~[hsqldb-2.4.0.jar:2.4.0]
    at org.hsqldb.ParserDQL.XreadSimpleTable(Unknown Source) ~[hsqldb-2.4.0.jar:2.4.0]
    at org.hsqldb.ParserDQL.XreadQueryPrimary(Unknown Source) ~[hsqldb-2.4.0.jar:2.4.0]
    at org.hsqldb.ParserDQL.XreadQueryTerm(Unknown Source) ~[hsqldb-2.4.0.jar:2.4.0]
    at org.hsqldb.ParserDQL.XreadQueryExpressionBody(Unknown Source) ~[hsqldb-2.4.0.jar:2.4.0]
    at org.hsqldb.ParserDQL.XreadQueryExpression(Unknown Source) ~[hsqldb-2.4.0.jar:2.4.0]
    at org.hsqldb.ParserDQL.compileCursorSpecification(Unknown Source) ~[hsqldb-2.4.0.jar:2.4.0]
    at org.hsqldb.ParserCommand.compilePart(Unknown Source) ~[hsqldb-2.4.0.jar:2.4.0]
    at org.hsqldb.ParserCommand.compileStatement(Unknown Source) ~[hsqldb-2.4.0.jar:2.4.0]
    at org.hsqldb.Session.compileStatement(Unknown Source) ~[hsqldb-2.4.0.jar:2.4.0]
    at org.hsqldb.StatementManager.compile(Unknown Source) ~[hsqldb-2.4.0.jar:2.4.0]
    at org.hsqldb.Session.execute(Unknown Source) ~[hsqldb-2.4.0.jar:2.4.0]
    at org.hsqldb.jdbc.JDBCPreparedStatement.<init>(Unknown Source) ~[hsqldb-2.4.0.jar:2.4.0]
    at org.hsqldb.jdbc.JDBCConnection.prepareStatement(Unknown Source) ~[hsqldb-2.4.0.jar:2.4.0]
    at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.doPrepare(StatementPreparerImpl.java:146) ~[hibernate-core-5.2.12.Final.jar:5.2.12.Final]

正确的语法是什么？或者在 HSQLDB 中有更好的方法吗？

Answer 1

问题出在变量@rownum的使用上。 HSQLDB 不支持此功能。

使用 HSQLDB，您可以以简单的方式完成。

假设 table 称为 CUSTOMER，序列列称为 ID。下面的查询显示了 SEQUENCE_ARRAY 如何工作并用于查找缺失值。

-- this returns consecutive numbers within a fixed range
SELECT * FROM UNNEST (SEQUENCE_ARRAY(1, 1000, 1))
-- this returns all the possible consecutive numbers for an existing table
SELECT * FROM UNNEST (SEQUENCE_ARRAY((SELECT MIN(ID) FROM CUSTOMER), (SELECT MAX(ID) FROM CUSTOMER), 1))

-- this returns the list of unused IDs.
SELECT * FROM UNNEST (SEQUENCE_ARRAY((SELECT MIN(ID) FROM CUSTOMER), (SELECT MAX(ID) FROM CUSTOMER), 1)) SEQ(IDCOL)
LEFT OUTER JOIN CUSTOMER ON CUSTOMER.ID = SEQ.IDCOL WHERE CUSTOMER.ID IS NULL

如何在 HSQLDB 中查找顺序编号中的空白？

How to find gaps in sequential numbering in HSQLDB?

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