Question

VB.NET操作SQL SERVER 2008数据库，想把文本框中输入的字符串转化为数字进行数据库的更新，却一直失败

更新语句如下：
Private Sub btUpdate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btUpdate.Click

Dim x As Int16 = Int16.Parse(TxtPerson.Text)

Dim sql As String = "UPDATE COURSEINFO SET REALLENGTH=x WHERE TEACHERID='" + TxtNum.Text + "'"
Dim dt As DataTable = GetDataTable(sql)
Dim sqlCmd As New SqlCommand
sqlCmd.Connection = SqlCon
sqlCmd.CommandText = sql

Try
SqlCon.Open()
sqlCmd.ExecuteNonQuery()
MessageBox.Show("修改记录成功")
Catch ex As Exception
MessageBox.Show("修改记录失败")
WriteErr(ex)
Finally
SqlCon.Close()
End Try
End Sub
End Class
求高手指导为什么一直不成功，更新语句格式有错吗？

Answer 1

更新的字符串有问题，你要更新的是X的值，而不知"X"，所以应该如下：
Dim sql As String = "UPDATE COURSEINFO SET REALLENGTH=“ & cstr(x) & " WHERE TEACHERID='" + TxtNum.Text + "'"
其他的语句没看出有错。

Answer 2

Dim sql As String = "UPDATE COURSEINFO SET REALLENGTH=x WHERE TEACHERID='" + TxtNum.Text + "'"
修改为：
Dim sql As String = "UPDATE COURSEINFO SET REALLENGTH=x WHERE TEACHERID=" & TxtNum.Text
PS：
VB中字符串的连接最好使用&符号，不要使用+符号