List Creator

This is one of my favorite pieces of code I've stolen borrowed from another site. I've had made some minor code changes and additions from the original, but basically I just need to send in a DataReader after running a sql command and it will return a list of objects of that type. (Very similar to Linq to Sql)

You just need to make sure that anything that is return through the query is defined in the object as a write property.

So here is the List Creator code, which does the creation via reflections:

Code Snippet

1. public class ListCreator where T : new()
2. {
3.      public List FindAll(IDataReader iDataReader)
4.      {
5.          List returnList = new List();
6.  
7.          try
8.          {
9.              //need a Type and PropertyInfo object to set properties via reflection
10.              Type tType = new T().GetType();
11.              PropertyInfo pInfo;
12.  
13.              //x will hold the instance of until it is added to the list
14.              T x;
15.  
16.              //use reader to populate list of objects
17.              while (iDataReader.Read())
18.              {
19.                  x = new T();
20.  
21.                  //set property values
22.                  //for this to work, command’s column names must match property names in object
23.                  for (int i = 0; i < iDataReader.FieldCount; i++)
24.                  {
25.                      pInfo = tType.GetProperty(iDataReader.GetName(i));
26.  
27.                      pInfo.SetValue(x, (iDataReader[i] == DBNull.Value? null:iDataReader[i]), null);
28.                  }
29.  
30.                  //once instance of is populated, add to list
31.                  returnList.Add(x);
32.              }
33.          }
34.          catch (Exception ex)
35.          {
36.              Logging.Logging.Error(ex.ToString());
37.          }
38.  
39.          return returnList;
40.      }
41. }

So in my DAL I might have something like:

Code Snippet

1. public List<PartsOrdering> GetAllPartsOrdering()
2. {
3.    List<PartsOrdering> li = new List<PartsOrdering>();
4.    try
5.    {
6.       using (SqlConnection cn = new SqlConnection(connString))
7.       {
8.           ListCreator<PartsOrdering> PartsOrders = new ListCreator<PartsOrdering>();
9.           SqlCommand cmd = new SqlCommand("dbo.selPartsOrdering", cn);
10.           cmd.CommandType = CommandType.StoredProcedure;
11.           cn.Open();
12.           li = PartsOrders.FindAll(ExecuteReader(cmd));
13.       }
14.   }
15.   catch (Exception ex)
16.   {
17.      Logging.Error(ex.ToString());
18.   }
19.   return li;
20. }

Code Snippet

1. [Serializable]
2. public class PartsOrdering : IFormattable
3. {
4.     #region Properties
5.     [DefaultValue(-1)]
6.     public int PartsOrderingID
7.     {
8.         get;
9.         set;
10.     }
11.     [DefaultValue("")]
12.     public string ToolID
13.     {
14.         get;
15.         set;
16.     }
17.     [DefaultValue("")]
18.     public string PartNumber
19.     {
20.         get;
21.         set;
22.     }
23.     [DefaultValue("")]
24.     public string Description
25.     {
26.         get;
27.         set;
28.     }
29.     [DefaultValue(0)]
30.     public int Quantity
31.     {
32.         get;
33.         set;
34.     }
35.     [DefaultValue(1)]
36.     public int PartsOrderingLocationID
37.     {
38.         get;
39.         set;
40.     }
41.     [DefaultValue(1)]
42.     public int PartsOrderingUrgencyID
43.     {
44.         get;
45.         set;
46.     }
47.     [DefaultValue("")]
48.     public string Comment
49.     {
50.         get;
51.         set;
52.     }
53.     public DateTime RequestedDateTime
54.     {
55.         get;
56.         set;
57.     }
58.     [DefaultValue("")]
59.     public string RequestedUser
60.     {
61.         get;
62.         set;
63.     }
64.     public string LocationName
65.     {
66.         get
67.          {
68.              List&lt;PartsOrderingLocation&gt; locations = new PartsOrderingLocation().List();
69.              return locations.Where(n =&gt; n.PartsOrderingLocationID.Equals(this.PartsOrderingLocationID)).Select(n =&gt; n.Name).First();
70.          }
71.         set
72.          {
73.              List&lt;PartsOrderingLocation&gt; locations = new PartsOrderingLocation().List();
74.              this.PartsOrderingLocationID = locations.Where(n =&gt; n.Name.Equals(value)).Select(n =&gt; n.PartsOrderingLocationID).First();
75.          }
76.  
77.     }
78.     public string UrgencyName
79.     {
80.         get
81.          {
82.              List&lt;PartsOrderingUrgency&gt; locations = new PartsOrderingUrgency().List();
83.              return locations.Where(n =&gt; n.PartsOrderingUrgencyID.Equals(this.PartsOrderingUrgencyID)).Select(n =&gt; n.Name).First();
84.          }
85.         set
86.          {
87.              List&lt;PartsOrderingUrgency&gt; locations = new PartsOrderingUrgency().List();
88.              this.PartsOrderingUrgencyID = locations.Where(n =&gt; n.Name.Equals(value)).Select(n =&gt; n.PartsOrderingUrgencyID).First();
89.          }
90.     }
91.     public int UrgencyRank
92.     {
93.         get
94.          {
95.              List&lt;PartsOrderingUrgency&gt; locations = new PartsOrderingUrgency().List();
96.              return locations.Where(n =&gt; n.PartsOrderingUrgencyID.Equals(this.PartsOrderingUrgencyID)).Select(n =&gt; n.Rank).First();
97.          }
98.     }
99.     [DefaultValue(-1)]
100.     public int PartsOrderingGroupID
101.     {
102.         get;
103.         set;
104.     }
105.     [DefaultValue(true)]
106.     public bool IsActive
107.     {
108.         get;
109.         set;
110.     }
111. }

How to update large count of rows without locking them

Found this interesting, how to update large databases, so that you don't have to lock rows
http://blogs.msdn.com/sqlpfe/archive/2010/01/06/tsql-coding-patterns-i.aspx

So instead of the usual:

 UPDATE dbo.Foo

SET Column = 'Value'

Try:

DECLARE @UpdatedRows(PK_Id int NOT NULL PRIMARY KEY)

DECLARE @var INT

SELECT @var=0 -- this resets @@ROWCOUNT=1

WHILE @@ROWCOUNT >0

BEGIN

UPDATE TOP(1500) BAR

  SET Column='Value'

OUTPUT inserted.PK_ID

INTO  @UpdatedRows

FROM  dbo.BAR as BAR

WHERE NOT EXISTS (SELECT 1 FROM @UpdatedRows UPD WHERE UPD.PK_ID=BAR.PK_ID)

END

I prefer one of the ways the commentator offered: (easier to follow)

WHILE @@ROWCOUNT >0

BEGIN

 UPDATE TOP(1500) BAR

   SET Column='Value'

 WHERE

   Column <> 'Value'

END