Audit Trail Trigger generation

Question

Working on Audit Trail system and decided to do it with Shadow/History table with triggers.

Followed this Audit Trail Article and trying to use CodeSmith Generator tool

I dont understand how it creates the history table and the trigger.

Is any one could understand how it works and help me on it.

I tried google to understand it. But there is no clear example

Nothing is clear with the below to me

Audit Table looks like this

 CREATE TABLE [dbo].[<%= AuditTableName %>] (
    [ChangeLogID] [int] IDENTITY (1, 1)  ,
    [OperationType] [varchar] (10) NOT NULL ,
    [ChangeTimestamp] [datetime] NOT NULL ,
    [MadeBy] [varchar] (6)  NOT NULL ,
    [TableChanged] [varchar] (50)  NOT NULL 
 ) ON [PRIMARY]

Detail Table looks like this

 CREATE TABLE [dbo].[<%= AuditFieldTableName %>] (
    [FieldName] [varchar] (50) NOT NULL ,
    [ChangeLogID] [int] NOT NULL ,
    [BeforeValue] [sql_variant]  NOT NULL ,
    [AfterValue] [sql_variant] NOT NULL 
 ) ON [PRIMARY]

How to generate this and add trigger and how can i insert AuditFieldTableName values?

Answer 1

As we have different types of columns in multiple tables, the audit table that you have specified wouldn't really suffice the cause. I suggest the following audit table:

TABLE auditEntry (
    auditEntryId           INTEGER      PRIMARY KEY,
    operationType          VARCHAR(10)  NOT NULL,      -- For INSERT / UPDATE / DELETE
    changeTimestamp        DATETIME     NOT NULL,
    madeBy                 VARCHAR(50)  NOT NULL,
    tableName              VARCHAR(30)  not null,      -- stores the name of the table changed
    columnName             VARCHAR(30)  not null,      -- stores the name of column changed
    oldInt                 INTEGER,
    newInt                 INTEGER,
    oldVarchar             VARCHAR(100),
    newVarchar             VARCHAR(100),
    oldDate                DATETIME,
    newDate                DATETIME)

Now I think it's a cakewalk for you to write row level triggers for INSERT , UPDATE and DELETE on your tables, if you have working knowledge of writing them. Search MSDN on how to write such triggers and you will be fine.