C#

...
SqlCommand comm = new SqlCommand("Update table_name set proj_id = @newpid where proj_id = @oldpid");
...
comm.Parameters.AddWithValue("@newpid", newpid); 
comm.Parameters.AddWithValue("@oldpid", oldpid);
...

protected void Page_Load(object sender, EventArgs e)
{
 if (!this.IsPostBack)
 {
   // It did display the first(old) project id into the textbox.
   String projectID = (String)Session["projId"];
   txtProjId.Text = projectID;
 }
}

txtProjId.Text = (String)Session["projId"];

szolDat wrote:

When you use "for" cycles you have to use lock if more than one thread is executing that part because they may interfere with each other when incrementing the cycle-variable.

szolDat wrote:

This way multiple threads can access a cycle instead of waiting until the running thread exits the lock. What do you think?

namespace Template
{
    public partial class Template
    {
        private int[] values ;
        private int   classi ;
 
        public Template
        (
            int HowMany
        )
        {
            this.values = new int [ HowMany ] ;
 
            for ( int i = 0 ; i < HowMany ; i++ )
            {
                this.values [ i ] = i ;
            }
 
            return ;
        }
 
        public void
        PrintLocal
        (
            object Format
        )
        {
            for ( int locali = 0 ; locali < this.values.Length ; locali++ )
            {
                System.Console.Write
                (
                    (string) Format
                ,
                    this.values [ locali ]
                ) ;
            }
 
            return ;
        }
 
        public void
        PrintClass
        (
            object Format
        )
        {
            for ( this.classi = 0 ; this.classi < this.values.Length ; this.classi++ )
            {
                System.Console.Write
                (
                    (string) Format
                ,
                    this.values [ this.classi ]
                ) ;
            }
 
            return ;
        }
 
        public void
        PrintClassWithLock
        (
            object Format
        )
        {
            lock ( this.values )
            {
                for ( this.classi = 0 ; this.classi < this.values.Length ; this.classi++ )
                {
                    System.Console.Write
                    (
                        (string) Format
                    ,
                        this.values [ this.classi ]
                    ) ;
                }
            }
            
            return ;
        }
 
        [System.STAThreadAttribute]
        public static int
        Main
        (
            string[] args
        )
        {
            int result = 0 ;
 
            Template t = new Template ( 100 ) ;
 
            try
            {
                System.Threading.Thread a = new System.Threading.Thread ( t.PrintLocal ) ;
                System.Threading.Thread b = new System.Threading.Thread ( t.PrintLocal ) ;
 
                a.Start ( " A({0:00})" ) ;
                b.Start ( " B({0:00})" ) ;
 
                while ( a.IsAlive && b.IsAlive )
                {
                    System.Threading.Thread.Sleep ( 100 ) ;
                }
         
                System.Threading.Thread c = new System.Threading.Thread ( t.PrintClass ) ;
                System.Threading.Thread d = new System.Threading.Thread ( t.PrintClass ) ;
 
                System.Console.WriteLine() ;
                System.Console.WriteLine() ;
                
                c.Start ( " C({0:00})" ) ;
                d.Start ( " D({0:00})" ) ;
 
                while ( c.IsAlive && d.IsAlive )
                {
                    System.Threading.Thread.Sleep ( 100 ) ;
                }
         
                System.Threading.Thread e = new System.Threading.Thread ( t.PrintClassWithLock ) ;
                System.Threading.Thread f = new System.Threading.Thread ( t.PrintClassWithLock ) ;
 
                System.Console.WriteLine() ;
                System.Console.WriteLine() ;
                
                e.Start ( " E({0:00})" ) ;
                f.Start ( " F({0:00})" ) ;
 
                while ( e.IsAlive && f.IsAlive )
                {
                    System.Threading.Thread.Sleep ( 100 ) ;
                }
            }
            catch ( System.Exception err )
            {
                System.Console.Write ( err.Message ) ;
            }
 
            return ( result ) ;
        }
    }
}

szolDat wrote:

Please explain why the following situation isn't possible (I'm somewhat clear about the heap and the stack):
Thread1 enters the cycle, increments i by 1.
The control is passed to Thread2 and it enters the cycle too, incrementing i by 1. i now equals 2.
Thread1 gets control again and tries to access an array's element (or perform any action) using the cycle variable.