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Core Code Modern Dev Handbook

SQL Insert Into Select

INSERT INTO SELECT copies data from one table into another existing table.
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SQL INSERT INTO SELECT

The INSERT INTO SELECT statement copies data from one table and inserts it into an existing table.

Basic Syntax

INSERT INTO target_table (column1, column2, ...)
SELECT column1, column2, ...
FROM source_table
WHERE condition;

Example: Copy Active Customers

Insert active customers into an archive table:

INSERT INTO archived_customers (id, name, email)
SELECT id, name, email
FROM customers
WHERE status = 'active';

Copy All Columns

If both tables have the same structure and column order:

INSERT INTO archived_customers
SELECT *
FROM customers
WHERE status = 'inactive';

Using JOIN with INSERT INTO SELECT

You can insert results from a JOIN query:

INSERT INTO customer_orders_summary (customer_name, order_date)
SELECT c.name, o.order_date
FROM customers AS c
JOIN orders AS o
  ON c.id = o.customer_id;

Important Rules

  • The number of columns in INSERT must match the SELECT
  • Data types must be compatible
  • Target table must already exist

Duplicate Data Risk

If you run the same INSERT INTO SELECT multiple times, you may insert duplicate rows unless prevented by constraints.

Performance Note

On large datasets, this operation may lock tables or consume significant resources. Proper indexing and batching may be necessary.

Common Mistakes

  • Mismatched column counts
  • Wrong column order
  • Forgetting WHERE when only partial data is intended

Next Step

Continue with SQL CASE to learn conditional logic inside queries.

SQL Case →