Oracle sql 添加自定义列名作为结果集的第一行

Question

如何将列名作为结果集的第一行。我在下面尝试但得到如下所示的错误

select 'First Name', 'Last Name', 'Middle Name', 'Term Number', 'BID', 'BTitle', 'SubB Name', 'LNum' from dual 
    UNION
    select
                pa.first_name as first_name,
                pa.last_name as last_name,
                pa.MIDDLE_INITIAL as middle_name,
                bi.bi_num as num,
                bi.b_id as bId,
                b.name as b_title,
                bi.sub_board_name as sub_b_name,         
                pa.L_NUMBER as lNum
            from
                M_INFO pa,
                B_INV bi,
                Blot b,
                users u,
                roles r  
            where
                bi.assigned_to  = u.bi_num(+) 
                and bi.bi_num = pa.bi_num(+) 
                and u.role_id = r.id(+)  
                and bi.b_id = b.id
                and bi.delete_dt is null  
                and bi.delete_by is null  
                and bi.ARCHIVED_DT is null  
                and bi.b_id = '40'  and bi.sub_b_name = 'TEST'; 


ORA-01790: expression must have same datatype as corresponding expression
01790. 00000 -  "expression must have same datatype as corresponding expression"
*Cause:    
*Action:
Error at Line: 1 Column: 50

Answer 1

我建议对您的查询进行两项更改。

1. 更改UNION到UNION ALL 。 这样您的联合就不会在联合的两个部分之间寻找重复项。
2. 由于联合的第一部分是所有字符串，联合的第二部分也需要返回所有字符串。 联合的第二部分中的任何数字列都需要转换为字符串。 示例：将bi.bi_num更改为TO_CHAR(bi.bi_num)