使用复合键删除 [英] Delete using composite key

问题描述

我有一个表，该表具有付款目的和付款日期作为组合键.我正在尝试
使用我的表单从表中删除一行.代码正在运行，但没有从表中删除行
表单后面的代码

I have a table which has purpose and dateofpayment as it composite key. I am trying
to use my form to delete a row from the table. The code is running but it is not deleting the row from the table
code behind the form

private void btnDelete5_Click(object sender, EventArgs e)
{
            clsStaffsalarypayment person5 = new clsStaffsalarypayment();

            if (MessageBox.Show("Are you really sure of the deletion", "Deletion", MessageBoxButtons.YesNo) == DialogResult.No)
            {
                return;
            }
            else
            {
                person5.ID5 = this.cboStaffid5.Text;
                //person.savehistory();a
                person5.removeRegister5();
            }
}

类中的代码

code in class

public void removeRegister5()
{
            //remove the data in memory


            SqlCommand cmd = new SqlCommand();
            string dat = null;
            dat = dateofpayment.Year + "-" + dateofpayment.Month + "-" + dateofpayment.Day;

            string sqlQuery = null;
            sqlQuery = "delete from tblstaffsalarypaymentdetails where purpose = '" + purpose + "' and dateofpayment ='" + dat + "'";
            cmd.Connection = conn;
            cmd.CommandText = sqlQuery;
            cmd.CommandType = System.Data.CommandType.Text;
            conn.Open();
            cmd.ExecuteNonQuery();
            conn.Close();
            cmd.Dispose();
}

推荐答案

在生成查询字符串的行(即sqlQuery = "delete from tblstaffsalarypaymentdetails where purpose = ''" + purpose + "'' and dateofpayment =''" + dat + "''";.)上放置一个断点. 一旦程序停止执行，请将此查询复制到sql Server Management Studio中并运行它(替换参数后).
检查结果-它最有可能帮助您找到解决方案.

Put a breakpoint on the line that builds the query string i.e. sqlQuery = "delete from tblstaffsalarypaymentdetails where purpose = ''" + purpose + "'' and dateofpayment =''" + dat + "''";.
Once the program stops execution, copy this query into sql server management studio and run it (after replacing the parameters).
Check the result - it should most likely help you get to the solution.

您好

它不会删除，因为条件返回false.检查目的是否正确，然后必须检查数据.如果所有这些都正确，请尝试以下操作:

Hello

It doesn''t delete because the condition returns false. Check the purpose if it''s correct then you must check the dat. If all of these are correct then try this:

sqlQuery = "delete from tblstaffsalarypaymentdetails where purpose = N'" + purpose + "' and dateofpayment ='" + dat + "'";

有人建议:
1.不要在查询后使用conn.Close()，因为如果conn.Close之前存在异常，则连接永远不会关闭.
在finally块中使用它.或使用using

2.代码不需要else:

Some advises:
1. Do not use conn.Close() after a query because if there be an exception before than conn.Close then the connection never be closed.
Use it in a finally block. or use using

2. The code dosn''t need else:

if (MessageBox.Show("Are you really sure of the deletion", "Deletion", MessageBoxButtons.YesNo) == DialogResult.No)
{
    return;
}
//else
//{
person5.ID5 = this.cboStaffid5.Text;
//person.savehistory();a
person5.removeRegister5();
//}

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