jOOQ子查询给出了编译错误“ SelectWhereStep…类型的where（Condition ...）方法不适用于自变量

Question

): 我在子查询的上收到以下编译器错误 ）：

SelectWhereStep <Record1 <String >>类型的where（Condition ...）方法不适用于参数（TableField <IfsHelpRecord，Long>）

当我有以下jOOQ子查询代码时：

  IfsHelp parentHelp = IFS_HELP.as( "parentHelp" ); Field<Object> parent_help_subject = sqlca .select( IFS_HELP.SUBJECT_NAME ) .from( parentHelp ) .where( parentHelp.SUBJECT_ID = IFS_HELP.PARENT_SUBJECT_ID ) .asField( "parent_help_subject" ); results = sqlca .select( IFS_HELP.SUBJECT_NAME, IFS_HELP.SUBJECT_ID, parent_help_subject ) .from( IFS_HELP ) .where( IFS_HELP.HELP_TEXT.like( argument ) ) .and( IFS_HELP.DISPLAY.equal( "Y" ) ) .orderBy( IFS_HELP.SUBJECT_NAME.asc() ) .limit( 50 ) .fetch(); 

数据库表如下所示：

IFS_HELP
  SUBJECT_ID (bigint, pk)
  SUBJECT_NAME (varchar)
  PARENT_SUBJECT_ID (bigint, fk back to ifs_help.subject_id)
  HELP_TEXT (varchar)
  DISPLAY (char)

这是我要执行的查询：

  SELECT ifs_help.subject_name, ifs_help.subject_id, ifs_isNull( ( select subject_name from ifs_help P where P.subject_id = ifs_help.parent_subject_id ), '' ) as parent_help_subject FROM ifs_help WHERE ifs_help.help_text like argument AND ifs_help.display = 'Y' ORDER BY ifs_help.subject_name ASC LIMIT 50 

Answer 1

这是一个简单的错字。 如果在像jOOQ这样的内部DSL中实现以下功能，那就太好了：

.where( parentHelp.SUBJECT_ID = IFS_HELP.PARENT_SUBJECT_ID )
//                            ^ Redefined semantics of assignment operator

但事实并非如此。 您无法在Java中重新定义赋值运算符的语义。 因此，您必须改为使用eq()或equal()方法：

.where( parentHelp.SUBJECT_ID.eq(IFS_HELP.PARENT_SUBJECT_ID) )