C＃类库SQL插入选择

Question

I'm trying to write a C# Class that will allow me to audit off data from a Live table to an Audit table in SQL. Showing a complete history of changes made to the data.

INSERT INTO tbl_audit SELECT * FROM tbl_data WHERE ID = id

I've got that one working ok if the two tables columns match ok in my Class Library, what I really need to do is able to define columns:

INSERT INTO tbl_audit (cols) SELECT (vars) FROM tbl_data WHERE ID = id

Can someone explain how i can loop through each col passing through the required variable? Is it even possible? So it would look like:

INSERT INTO tlb_audit (col1, col2, col3) SELECT (col1, col2, col3) FROM tbl_data WHERE ID = id

my code would look something like:

class.connection = myconnection.cs
class.currenttable = "tbl_data"
class.newtable = "tbl_audit"

class.col("sqlColumn1_in_tbl_audit")
class.col("sqlColumn1_in_tbl_data")

class.col("sqlColumn2_in_tbl_audit")
class.col("sqlColumn2_in_tbl_data")

etc

class.commit

Answer 1

You can use a script like this to get the table column names:

SELECT COLUMN_NAME 
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'YourTableName' AND TABLE_SCHEMA='YourSchemaName'

Once you get back the result you can loop through the names to build your INSERT query. I'm not sure how this gives you auditing on the table though. I think you might be better off building that functionality using the DBMS, maybe using Triggers

Answer 2

Here is what I do to email notifications for audited tables in one of our applications. It reads the entity state from EntityFramework's data context and formats the changes as a formatted json string.

public override int SaveChanges()
{

    var auditChanges = ChangeTracker.Entries()
            .Where(t => t.State != EntityState.Unchanged && t.Entity.GetType().IsDefined(typeof(AuditAttribute),true))
            .Select(t =>
            {
                var entityType = t.Entity.GetType();
                if (entityType.BaseType != null && entityType.Namespace == "System.Data.Entity.DynamicProxies")
                {
                    entityType = entityType.BaseType;
                }
                return new
                {
                    entityType.Name,
                    State = t.State.ToString(),
                    Changes = t.State == EntityState.Deleted ? null : t.CurrentValues.PropertyNames
                        .Where(pn => t.State == EntityState.Added || t.CurrentValues[pn] == null && t.OriginalValues[pn] != null || t.CurrentValues[pn] != null && !(t.CurrentValues[pn].Equals(t.OriginalValues[pn])))
                        .ToDictionary(pn => pn, pn => t.CurrentValues[pn]),
                    Original = t.State == EntityState.Added ? null :
                        t.OriginalValues.PropertyNames.ToDictionary(pn => pn,
                            pn => t.OriginalValues[pn])
                };
            });

    if (auditChanges.Any())
    {
        var auditMessage = new StringBuilder(2048);

        var changes = JsonConvert.SerializeObject(auditChanges, Formatting.Indented);

        auditMessage.AppendFormat("Timestamp: {0}\r\nUser: {1}\r\nIP Address: {2}\r\n====================\r\n{3}\r\n",
            DateTime.Now, HttpContext.Current == null || HttpContext.Current.User == null ? "" : HttpContext.Current.User.Identity.Name,
        Controllers.BaseController.GetIpAddress(HttpContext.Current),changes);

    NotificationManager.SendNotifications(NotificationType.Audit, this, GetDataSession(),null,auditMessage.ToString());
    }
    retval = base.SaveChanges();
}

I tag classes to be audited with this audit attribute:

public class AuditAttribute : Attribute { }

Like so:

[Audit]
public partial class Agency { }

If not using a framework, you'll need a way of identifying before and after snapshots of your table rows in order to build something similar. You could also store your audit log into the database or using a syslog style logging api.

Sample Audit Table:
Timestamp Date,
EntityName varchar2(50),
Changes varchar2(MAX)?

Here is a sample email that we get when someone changes a tracked table:

The following database changes were made to tracked objects:

Timestamp: 11/13/2015 2:02:34 PM
User: 
IP Address: 173.165.34.65
====================
[
 {
   "Name": "CarrierSetting",
   "State": "Modified",
   "Changes": {
     "DirectBill": true
   },
   "Original": {
     "Id": 531,
     "CarrierCode": "MEXIC",
     "AllowQuote": true,
     "AllowBOL": true,
     "DirectBill": false,
     "RequireDocusign": false,
   }
 }
]

The nice thing about this is that you could theoretically reconstruct the database at the time of the change by deserializing the Json strings.