未定义的函数'concat' vb.net [重复]

Posted 2023-05-06

【中文标题】未定义的函数\'concat\' vb.net [重复]

【英文标题】：undefined function 'concat' vb.net [duplicate]未定义的函数'concat' vb.net [重复]

【发布时间】：2018-02-24 17:42:49

【问题描述】：

我在连接我的 sql 中的 2 列时遇到问题。有人可以检查我的 concat 语句中出了什么问题。

查询：

Public Function getStudents(ByVal oStudentsBO As StudentsBO) As DataTable
    dt = New DataTable
    sql = "SELECT [KY_ID_NUM] as [ID Num], [NM_NICK] as [Nick Name], [CD_AGE_GROUP] as [Age Group], " &
          "[NM_LAST] as [Last Name], [NM_FIRST] as [First Name], " &
          "CONCAT(NM_GFIRST, NM_GLAST) FROM [tblStudents] " &
          "WHERE [NM_FIRST] Like '%" & oStudentsBO.NM_FIRST & "%'" &
          "OR [NM_NICK] LIKE '%" & oStudentsBO.NM_NICK & "%'" &
          "OR [NM_LAST] Like '%" & oStudentsBO.NM_LAST & "%'"
    dt = oDA.getDataTable(sql)
    Return dt
End Function

错误：

【问题讨论】：

您使用的是哪个 DBMS 和版本？请复制并粘贴您的代码为文本

什么是下划线数据库？

下划线数据库是什么意思？

Oracle（哪个版本10g、11g、12g）、mysql（哪个版本）、SQLServer等。我从查询中猜是SQLServer。

MS 访问没有 CONCAT 函数。使用字符串连接。

【参考方案1】：

MS Access 没有函数 CONCAT。相反，您必须使用字符串连接：

Public Function getStudents(ByVal oStudentsBO As StudentsBO) As DataTable
    dt = New DataTable
    sql = "SELECT [KY_ID_NUM] as [ID Num], [NM_NICK] as [Nick Name], [CD_AGE_GROUP] as [Age Group], " &
          "[NM_LAST] as [Last Name], [NM_FIRST] as [First Name], " &
          " [NM_GFIRST] & [NM_GLAST] FROM [tblStudents] " &
          "WHERE [NM_FIRST] Like '%" & oStudentsBO.NM_FIRST & "%'" &
          "OR [NM_NICK] LIKE '%" & oStudentsBO.NM_NICK & "%'" &
          "OR [NM_LAST] Like '%" & oStudentsBO.NM_LAST & "%'"
    dt = oDA.getDataTable(sql)
    Return dt
End Function