Append Queries vs. Merge Queries | Power BI || Belayet Hossain

"Append" and "Merge" operations are used to combine data from multiple tables, but they serve different purposes and are used in different scenarios.

𝐀𝐩𝐩𝐞𝐧𝐝:

-Use Case: The Append operation is used when you want to combine rows from two or more tables into a single table. This is useful when you have similar structured data (same columns) across multiple tables and you want to consolidate it into one table.

𝗛𝗼𝘄 𝗜𝘁 𝗪𝗼𝗿𝗸𝘀:

-Rows: Appending adds rows from the second (or more) table(s) to the first table.

-Columns: The tables involved in the Append operation must have the same column structure. If there are extra columns in one table that don’t exist in the others, those columns will have null values in the resulting table.

𝗘𝘅𝗮𝗺𝗽𝗹𝗲:

If you have two sales tables, one for 2023 and another for 2024, you can append them to create a combined sales table for both years.

𝗣𝗮𝘁𝗵 𝗶𝗻 𝗣𝗼𝘄𝗲𝗿 𝗕𝗜:

𝙷𝚘𝚖𝚎 𝚝𝚊𝚋 in Desktop > 𝚃𝚛𝚊𝚗𝚜𝚏𝚘𝚛𝚖 𝚍𝚊𝚝𝚊 to open the Power Query Editor > 𝙷𝚘𝚖𝚎 𝚝𝚊𝚋 in PQE > Click on 𝙰𝚙𝚙𝚎𝚗𝚍 𝚀𝚞𝚎𝚛𝚒𝚎𝚜 in the Combine group.

You can choose & Click OK

Append Queries : The original table is updated to include the appended rows from the other table(s).

Append Queries As New: A new table is created with the appended data, and the original tables are preserved.

𝐌𝐞𝐫𝐠𝐞:

-Use Case: The Merge operation is used when you want to join two tables based on a related column. This is helpful when you have tables with related data and want to combine them into a single table for analysis.

𝗛𝗼𝘄 𝗜𝘁 𝗪𝗼𝗿𝗸𝘀:

-Column: Merging is akin to performing a SQL JOIN operation. You can merge tables based on one or more columns that have common data (like a key).

-Join Type : You can specify different types of joins (Inner Join, Left Outer Join, Right Outer Join, etc.) based on how you want to merge the tables.

-Results: The resulting table will have the combined data based on the join conditions, with columns from both tables.

𝗘𝘅𝗮𝗺𝗽𝗹𝗲:

If you have a table of Orders and a table of Customers, and each order references a customer by a Customer ID, you can merge these tables on the Customer ID column to bring customer details into the Orders table.

𝐏𝐚𝐭𝐡 𝐢𝐧 𝐏𝐨𝐰𝐞𝐫 𝐁𝐈:

𝙷𝚘𝚖𝚎 𝚝𝚊𝚋 in Desktop > 𝚃𝚛𝚊𝚗𝚜𝚏𝚘𝚛𝚖 𝚍𝚊𝚝𝚊 > 𝙷𝚘𝚖𝚎 𝚝𝚊𝚋 in PQE > 𝙼𝚎𝚛𝚐𝚎 𝚀𝚞𝚎𝚛𝚒𝚎𝚜 in the Combine group.

> Choose the tables you want to merge.

> Select the column(s) to match from both tables.

> Choose the type of join you need (e.g., Left Join, Inner Join).

> Click OK

Merge Queries : The original table is replaced with the merged data.

Merge Queries As New: A new table is created, and both original tables remain intact.

Summary

𝙰𝚙𝚙𝚎𝚗𝚍 is for stacking tables with the same structure, adding rows together.

𝙼𝚎𝚛𝚐𝚎 is for joining tables based on related columns, combining rows based on a matching key.