How Can I Duplicate Data from One SQL Server Table to Another?

Efficiently Copying Data Between SQL Server Tables

This guide demonstrates how to duplicate data from one SQL Server table to another. We'll explore methods for copying data, handling differing schemas, and ensuring data integrity.

The simplest approach, suitable for tables with identical structures, involves a direct INSERT statement:

<code class="language-sql">INSERT INTO targetTable
SELECT * FROM sourceTable;</code>

Replace targetTable with the name of the destination table and sourceTable with the source table's name.

For tables with different column structures, you must explicitly map the columns:

<code class="language-sql">INSERT INTO targetTable (columnA, columnB, columnC)
SELECT columnX, columnY, columnZ
FROM sourceTable;</code>

Here, columnA, columnB, and columnC correspond to the columns in targetTable, and columnX, columnY, and columnZ are their respective counterparts in sourceTable. Careful attention must be paid to matching data types and order. While omitting the column list in the INSERT statement is possible if all columns are included in the SELECT statement and the order matches, explicit column mapping enhances readability and reduces the risk of errors.

Importantly, this INSERT method adds the copied data to the existing rows in targetTable; it does not overwrite existing data.

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