diff --git a/server/src/tables_data/handlers/post_table_data.rs b/server/src/tables_data/handlers/post_table_data.rs
index 41a04e5..bdfdb03 100644
--- a/server/src/tables_data/handlers/post_table_data.rs
+++ b/server/src/tables_data/handlers/post_table_data.rs
@@ -126,9 +126,24 @@ pub async fn post_table_data(
             .map_err(|e| Status::invalid_argument(e.to_string()))?;
 
         // Get source column from operation
-        let source_column = match operation {
-            ScriptOperation::SetToColumn { source } => source,
-        };
+        let source_column = 
+            match operation {
+                ScriptOperation::SetToLocalColumn { source } => source,
+                ScriptOperation::SetToExternalColumn { table, column } => {
+                    // For external columns, we need to resolve the value from the external table
+                    let external_source = format!("@{}.{}", table, column);
+                    let resolved_value = execution::resolve_value(
+                        db_pool, 
+                        profile_id, 
+                        &table_name, 
+                        &data, 
+                        &external_source
+                    ).await.map_err(|e| Status::invalid_argument(e.to_string()))?;
+                    
+                    // Return the resolved value
+                    resolved_value
+                }
+            };
 
         // Check source column presence
         let source_value = data.get(&source_column)