The REPLACE() function is a string function in SQL to replace all occurrences of a specified string with another string in the result set.

It is important to note that REPLACE() does not modify the data in the actual database table, it only alters the data in the query result.


SELECT REPLACE(first_name, 'John', 'Jonathan') AS updated_names
FROM Customers;

Here, the result set of this query replaces all occurrences of John with Jonathan in the first_name column of the Customers table.


The REPLACE() function can be combined with a WHERE clause for more precise replacements. For example,

SELECT REPLACE(item, 'Keyboard', 'Wireless Keyboard') AS updated_item
FROM Orders
WHERE amount < 500;

Here, the SQL command replaces Keyboard with Wireless Keyboard in the item column for orders where the amount is less than 500.

REPLACE() Within UPDATE Statement

IN SQL, we can also use REPLACE() within UPDATE statements for modifying the table data.

Let's take a look at an example.

UPDATE Shippings
SET status = REPLACE(status, 'Pending', 'In Transit')
WHERE customer IN (4, 5);

SELECT * FROM Shippings;

This SQL command updates the status column in the Shippings table, replacing Pending with In Transit for specific customers.

Chaining REPLACE() Functions

IN SQL, we can chain multiple REPLACE() functions for complex replacements. For example,

    REPLACE(REPLACE(last_name, 'Doe', 'Smith'), 'Robinson', 'Johnson')
    AS updated_last_name
FROM Customers;

This query replaces Doe with Smith and Robinson with Johnson in the last_name column.


IN SQL, we can also use REPLACE() with JOIN to perform replacements across multiple tables.

Let's take a look at an example.

    REPLACE(O.item, 'Keyboard', 'Mechanical Keyboard') AS updated_item
FROM Customers C
JOIN Orders O ON C.customer_id = O.customer_id;

In this example, Keyboard is replaced with Mechanical Keyboard in the item column while joining Customers and Orders tables.

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