SSIS CDC LSN Debugging nightmare second problem

Continuing the CDC debugging posts:

• Intro
• First Problem

Now that I have the StartLSN and EndLSN I was ready to go.  Hit my breakpoint and the variables were set appropriately.  Woo-hoo!

Then…wait a minute…what?

vSQLQuery.Value =
    "SELECT " +
    "    c.__$operation " +
    "    , c.Column1 " +
    "    , c.Column2 " +
    "    , ColumnN " +
    "FROM " +
    "    cdc.fn_cdc_get_net_changes_<instance_name>( " + sStartLSN + ",  " + sEndLSN + ", 'all') c";

That statement wasn’t changing the value of vSQLQuery.  huh?

Ok, I don’t by any stretch of the imagination claim to be an expert at C# but that looked pretty straight forward to me, however it wasn’t changing the value.

So now I start looking in earnest, google, bing, Stackoverflow, Serverfault, all to no avail.  This just wasn’t making sense.  I was about to call over an expert C# person (Magenic is full of them ) when I remembered that my previous problem was not a problem with the code but a problem with the configuration of the task.  So I start looking into the configuration of the script task and the variables that I was using and that’s where I saw it. 

vSQLValue was set to evaluate as an expression.  I had done this so I could copy and paste the SQL query I had developed in SSMS as opposed to making the query 1 line and pasting it into the value of the variable (the variable box in SSIS can’t interpret multi-line values, it only pastes the first line).

Turned off the fact that it was an expression and since it had already been evaluated it set the variable correctly (score!) and now I could manipulate the vSQLQuery.Value via the script task.

Now as to why I couldn’t modify a variable that is set to evaluate as an expression, I don’t know I’m sure there’s some sort of order of operations or locking catch here, but I still haven’t been able to find anything official about this.  Best I saw was this which would indicate to me that it would work.

Onto the next problem.

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