SSIS处理Azure数据至平面文件：新增CASE逻辑生成特定记录

Alright, let's walk through how to handle this SSIS requirement—generating that duplicate "Z" → "A" record only in your flat file output, no changes to the Azure source needed. Here's the playbook:

We'll split your data stream, modify the relevant records, filter only the ones that need duplication, then merge everything back together before writing to the flat file. No fancy tricks, just leveraging native SSIS transformations for efficiency.

• Step 1: Start with your existing data flow
  Keep your existing Azure source component (whether it's Azure SQL, Blob Storage, etc.) as is—we're not touching the source data.

• Step 2: Add a Multicast to split the stream
  Connect your source's output to a Multicast Transformation. This lets us send the same data to two separate paths: one for the original records, and one for the modified duplicates.

• Step 3: Modify the field in one branch
  Take one of the Multicast outputs and pipe it into a Derived Column Transformation. Let's say your target field is named Type—create a new column (or overwrite the existing one) with this expression:

  [Type] == "Z" ? "A" : [Type]
  

  This changes "Z" to "A" only for those rows, leaves others untouched.

• Step 4: Filter to keep only the "Z" records
  Right after the Derived Column, add a Conditional Split Transformation. Set up a condition like:

  [Type] == "Z"
  

  We only want to keep the modified rows that were originally "Z"—no need to duplicate non-"Z" records.

• Step 5: Merge the streams with Union All
  Now connect two inputs to a Union All Transformation:

  1. The original output from the Multicast (all your original records)
  2. The filtered output from the Conditional Split (only the modified "Z" → "A" records)
     Double-check that column names and data types match across both inputs—if you created a new column in the Derived Column, map it to the original field name here.

• Step 6: Write to your flat file
  Connect the Union All's output to your Flat File Destination, configure it like you normally would, and you're set. Your output will have the original records plus the duplicate "A" records for every "Z" entry.

If you need to handle more complex logic (like multiple fields or custom rules), a Script Component works too:

• Add a Script Component after your source, set it as a Transformation.
• In the Script Editor, select all input columns as ReadOnly, and make sure your output has matching columns.
• Use this C# snippet in the Input0_ProcessInputRow method (adjust column names to match your data):

  public override void Input0_ProcessInputRow(Input0Buffer Row)
  {
      // First, output the original row
      Output0Buffer.AddRow();
      Output0Buffer.Name = Row.Name;
      Output0Buffer.Age = Row.Age;
      Output0Buffer.Type = Row.Type;
      // Copy all other columns from the original row here
  
      // If the Type is "Z", output the modified duplicate
      if (Row.Type == "Z")
      {
          Output0Buffer.AddRow();
          Output0Buffer.Name = Row.Name;
          Output0Buffer.Age = Row.Age;
          Output0Buffer.Type = "A";
          // Copy all other columns exactly as original
      }
  }
  

  Then connect the Script Component's output to your flat file destination.

• No source changes: Both methods only modify the in-memory data stream—your Azure source stays untouched.
• Test first: Run with sample data that includes "Z" values to confirm both original and duplicate records show up in the flat file.
• Performance: The native transformation approach (Multicast + Conditional Split + Union All) is faster for large datasets than the Script Component, since it's optimized by SSIS.

内容的提问来源于stack exchange，提问作者Sql