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Merge DataTable

Merges two DataTables by combining their rows and columns. This operation uses .NET's DataTable.Merge() method, which intelligently combines table structures and data based on matching schemas.

Common Properties​

  • Name - The custom name of the node.
  • Color - The custom color of the node.
  • Delay Before (sec) - Waits in seconds before executing the node.
  • Delay After (sec) - Waits in seconds after executing node.
  • Continue On Error - Automation will continue regardless of any error. The default value is false.
info

If the ContinueOnError property is true, no error is caught when the project is executed, even if a Catch node is used.

Input​

  • First Table - First DataTable to merge (base table)
  • Second Table - Second DataTable to merge into the first table

Output​

  • Table - Merged DataTable containing combined data from both tables

Merge Behavior​

The Merge operation follows these rules:

  1. Matching Columns: If both tables have columns with the same name, rows are combined
  2. New Columns: Columns from the second table that don't exist in the first table are added
  3. Row Addition: Rows from the second table are added to the first table
  4. Schema Combination: The output has all unique columns from both tables

This is different from Append DataTable which requires identical column structures.

Example Usage​

Merging Tables with Same Structure​

// Table 1: ["ID", "Name", "Email"]
// 3 rows

// Table 2: ["ID", "Name", "Email"]
// 2 rows

// Result: Table with ["ID", "Name", "Email"]
// 5 rows total (3 + 2)

Merging Tables with Different Columns​

// Table 1:
// Columns: ["ID", "Name", "Email"]
// Row 0: ID=1, Name="John", Email="john@example.com"
// Row 1: ID=2, Name="Jane", Email="jane@example.com"

// Table 2:
// Columns: ["ID", "Phone", "Address"]
// Row 0: ID=1, Phone="555-1234", Address="123 Main St"
// Row 1: ID=3, Phone="555-5678", Address="456 Oak Ave"

// Result:
// Columns: ["ID", "Name", "Email", "Phone", "Address"]
// Row 0: ID=1, Name="John", Email="john@example.com", Phone="", Address=""
// Row 1: ID=2, Name="Jane", Email="jane@example.com", Phone="", Address=""
// Row 2: ID=1, Phone="555-1234", Address="123 Main St", Name="", Email=""
// Row 3: ID=3, Phone="555-5678", Address="456 Oak Ave", Name="", Email=""

Combining Data from Multiple Sources​

// Customer data from CRM system
// Table 1: ["CustomerID", "Name", "Email"]
// 500 customers

// Purchase history from billing system
// Table 2: ["CustomerID", "TotalPurchases", "LastOrderDate"]
// 300 customers (not all customers have made purchases)

// Merged result contains all columns and all customer records

Adding Supplementary Information​

// Base employee table
// Columns: ["EmployeeID", "Name", "Department"]

// Additional details table
// Columns: ["EmployeeID", "Phone", "Extension", "Location"]

// Merge to get complete employee information
// Result has all 6 columns

Enriching Data​

// Product catalog
// Table 1: ["SKU", "ProductName", "Category"]

// Inventory data
// Table 2: ["SKU", "Stock", "Warehouse", "ReorderPoint"]

// Merged table has complete product information
// Columns: ["SKU", "ProductName", "Category", "Stock", "Warehouse", "ReorderPoint"]

Tips​

  • Merge combines both schema (columns) and data (rows)
  • Unlike Append, tables don't need identical column structures
  • New columns are added automatically
  • Rows from both tables are preserved
  • Missing values in new columns are filled with empty/null values
  • Original tables remain unchanged
  • Use Merge when combining tables with different but related schemas
  • Use Append when stacking identical tables vertically

Common Errors​

Empty First Table Error​

Error: First table cannot be empty. Please provide a valid DataTable.

Solution: Ensure the first table input contains a valid DataTable object.

// Wrong
var firstTable = null;

// Correct
var firstTable = /* Valid DataTable */;

Empty Second Table Error​

Error: Second table cannot be empty. Please provide a valid DataTable.

Solution: Ensure the second table input contains a valid DataTable object.

// Wrong
var secondTable = null;

// Correct
var secondTable = /* Valid DataTable */;

Merge vs Append​

Understanding the difference:

Merge DataTable​

  • Purpose: Combine tables with different or similar structures
  • Column handling: Adds new columns from second table
  • Use when: Tables have different schemas but related data
  • Result columns: Union of all columns from both tables
  • Example: Combining customer details with purchase history

Append DataTable​

  • Purpose: Stack rows from tables with identical structure
  • Column handling: Requires matching columns
  • Use when: Tables have identical schemas
  • Result columns: Same as input tables
  • Example: Combining January and February sales data

Quick Comparison​

// Scenario 1: Same structure - Use Append
// Table 1: ["Name", "Age"]
// Table 2: ["Name", "Age"]
// Append Result: ["Name", "Age"] with combined rows

// Scenario 2: Different structure - Use Merge
// Table 1: ["Name", "Age"]
// Table 2: ["Name", "Email"]
// Merge Result: ["Name", "Age", "Email"] with combined rows

Advanced Usage​

Multi-Table Merge​

// Merge multiple tables sequentially
var result = /* First table */;

// Merge second table
// First Table: result
// Second Table: table2
// Output: result

// Merge third table
// First Table: result
// Second Table: table3
// Output: result

// Final result contains data from all tables

Conditional Merging​

// Only merge if certain conditions are met
var shouldMerge = /* some condition */;

if (shouldMerge) {
    // Merge DataTable node
    var mergedTable = /* output */;
} else {
    var mergedTable = firstTable;  // Use only first table
}

See Also​