Union功能存在问题？

[CHENPrime-coder]

环境：

• MySQL 8
• Ktorm 3.6.0

问题描述：

当我使用union函数尝试查询messageId大于指定ID的一条记录时，发现无论如何整个最终查询结果都只有一条。尝试将生成的SQL手动运行发现：

查询结果确实只有一条，我开始怀疑是不是少了个括号导致的，所以我尝试修改一下生成的SQL，并产生如下运行结果：

最后是我的DSL代码

        val currentAnswerAlias = Answer.aliased("current")
        val currentUserAlias = User.aliased("currentUser")
        val currentGroupAlias = Group.aliased("currentGroup")
        val currentTaskAlias = Task.aliased("currentTask")

        val nextAnswerAlias = Answer.aliased("next")
        val nextUserAlias = User.aliased("nextUser")
        val nextGroupAlias = Group.aliased("nextGroup")
        val nextTaskAlias = Task.aliased("nextTask")

        val query = database.from(currentAnswerAlias)
            .innerJoin(currentUserAlias, currentAnswerAlias.studentId eq currentUserAlias.id)
            .innerJoin(currentGroupAlias, currentUserAlias.groupId eq currentGroupAlias.id)
            .innerJoin(currentTaskAlias, currentAnswerAlias.taskId eq currentTaskAlias.id)
            .select(
                currentAnswerAlias.id,
                currentAnswerAlias.content,
                currentUserAlias.name,
                currentGroupAlias.name,
                currentTaskAlias.name,
            )
            .where { currentAnswerAlias.messageId eq messageId }
            .union(
                database.from(nextAnswerAlias)
                    .innerJoin(nextUserAlias, nextAnswerAlias.studentId eq nextUserAlias.id)
                    .innerJoin(nextGroupAlias, nextUserAlias.groupId eq nextGroupAlias.id)
                    .innerJoin(nextTaskAlias, nextAnswerAlias.taskId eq nextTaskAlias.id)
                    .select(
                        nextAnswerAlias.id,
                        nextAnswerAlias.content,
                        nextUserAlias.name,
                        nextGroupAlias.name,
                        nextTaskAlias.name,
                    )
                    .where { nextAnswerAlias.messageId greater messageId }
                    .limit(1)
            )

[CHENPrime-coder]

想了一下后，我发现我的功能并不需要union😂。不过我确实认为这个union可能存在一定的问题

[CHENPrime-coder]

存在重复issue，上午没仔细看😴 #497