Question

private void restoreBtn_Click(object sender, EventArgs e)
{
        try
        {
            if (databaseCmbBox.Text.CompareTo("") == 0)
            {
                MessageBox.Show("Please Select A Database");
                return;
            }
            con = new SqlConnection(connectionString);
            con.Open();
            sql = "ALTER DATABASE " + databaseCmbBox.Text  +" SET Single_User WITH Rollback Immediate ; RESTORE DATABASE " +
            databaseCmbBox.Text + " FROM DISK = @PATH WITH REPLACE ; ALTER DATABASE " + databaseCmbBox.Text + " SET Multi_User ;";
            comm.Parameters.AddWithValue("@PATH", databaseRestorePath.Text);
            comm.CommandTimeout = 86400000;


            //sql = "Alter Database "+databaseCmbBox.Text+" Set SINGLE_USER WITH ROLLBACK IMMEDIATE";
            //sql += "RESTORE Database " + databaseCmbBox.Text + " FROM DISK = '" + databaseRestorePath.Text + "' WITH REPLACE";
            comm = new SqlCommand(sql, con);
            comm.ExecuteNonQuery();

            con.Close();
            con.Dispose();
            MessageBox.Show("Database Succesfully Restored");

        }
        catch (Exception)
        {

            throw;
        }
}

请此代码抛出此错误，

类型＆＃39; System.Data.SqlClient.SqlException＆＃39;未处理的异常发生在WindowsFormsApplication1.exe
中
附加信息：必须声明标量变量＆＃34; @ PATH＆＃34;。

关键字＆＃39;附近有＆＃39;的语法不正确。如果此语句是公用表表达式，xmlnamespaces子句或更改跟踪上下文子句，则必须以分号结束前一个语句。

请问这段代码有什么错误？

Answer 1

在定义主查询字符串后，应添加参数。

 private void restoreBtn_Click(object sender, EventArgs e)
    {
        try
        {
            if (databaseCmbBox.Text.CompareTo("") == 0)
            {
                MessageBox.Show("Please Select A Database");
                return;
            }
            con = new SqlConnection(connectionString);
            con.Open();
            sql = "ALTER DATABASE " + databaseCmbBox.Text  +" SET Single_User WITH Rollback Immediate ; RESTORE DATABASE " +
            databaseCmbBox.Text + " FROM DISK = @PATH WITH REPLACE ; ALTER DATABASE " + databaseCmbBox.Text + " SET Multi_User ;";
            comm.CommandTimeout = 86400000;


            //sql = "Alter Database "+databaseCmbBox.Text+" Set SINGLE_USER WITH ROLLBACK IMMEDIATE";
            //sql += "RESTORE Database " + databaseCmbBox.Text + " FROM DISK = '" + databaseRestorePath.Text + "' WITH REPLACE";
            comm = new SqlCommand(sql, con);
            comm.Parameters.AddWithValue("@PATH", databaseRestorePath.Text);
            comm.ExecuteNonQuery();

            con.Close();
            con.Dispose();
            MessageBox.Show("Database Succesfully Restored");

        }
        catch (Exception)
        {

            throw;
        }

Answer 2

我认为您的代码存在一些混淆。在声明它之前使用comm变量（可能它也是一个错误）但是第一次

comm = new SqlCommand(sql, con);

然后

comm.Parameters.AddWithValue("@PATH", databaseRestorePath.Text);
comm.CommandTimeout = 86400000;

第二个显示完整的sqlcommand因为

sql = "ALTER DATABASE " + databaseCmbBox.Text  +" SET Single_User WITH Rollback Immediate ; RESTORE DATABASE " +

不完整（以+结尾）

第三我建议你在里面使用SqlConnection来确保它总是处理

using (SqlConnection connection = new SqlConnection(connectionString)) 
{}

数据库恢复出错

2 个答案: