如何生成自定义 ID [英] How to generate Custom ID

问题描述

我想为 ID 创建自定义值.例如，它将以CR00001"开头，之后当我第二次保存数据时，它将增加数字部分(例如CR00002).

I want to create a custom value for the ID. For example, it will start with "CR00001" and after that it will increment the numerical portion (e.g. CR00002) when I save the data for the second time.

这是我使用的代码:

 Dim cr_id As String
 cr_id = "CR00001"
 Dim iReturn As Boolean

 Using SQLConnection As New MySqlConnection(strConnectionString)
     Using sqlCommand As New MySqlCommand()
         sqlCommand.Connection = SQLConnection
         With sqlCommand
             .CommandText = "INSERT INTO cr_record(idcr_record,Emplid,isu,Nama,date1,DeptDesc,email,change1,reasonchange,problem,priority,reasondescription,systemrequest,attachment) VALUES (@cr_id,@Emplid,@isu,@Nama,@date1,@DeptDesc,@email,@change1,@reasonchange,@problem,@priority,@reasondescription,@systemrequest,@attachment)"
             .CommandType = Data.CommandType.Text
             .CommandTimeout = 5000
             .Parameters.AddWithValue("@cr_id", cr_id)

推荐答案

当你想生成一个新的 ID 时，编写一个生成 ID 的函数，并将这段代码复制到那里.保持返回类型为 String 以返回 newId.

When you want to generate a new ID, write one function for generating the ID, and copy this code there. Keep the return type as String to return newId.

    Dim newId As String
    Dim stringId As String
    Dim intId As Integer
    Dim conn As New System.Data.SqlClient.SqlConnection("Your database query string")
    Dim adpt As New System.Data.SqlClient.SqlDataAdapter("Select id from tableName Where date = (SELECT max(date) from tableName)", conn) 'Where tableName is you table
    Dim ds As New DataSet
    adpt.Fill(ds)
    If ds.Tables(0).Rows.Count = 0 Then 'This will check whether any records are there or not
        newId = "CR00001" ' If records are not there then this id will be returned
    Else
        stringId = ds.Tables(0).Rows(0).Item(0).ToString    'This will store your id in string format
        intId = stringId.Substring(2)       ' This will store only integer values from that id
        intId += 1      ' Increment id by 1
        newId = String.Concat("CR", intId)      ' Creating new Id incremented by 1
    End If
    Return newId

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