How to modify data in sql

There are three main ways to modify data in SQL: UPDATE statement: Modify existing data and specify the columns and conditions to be updated. INSERT statement: Inserts a new row, specifying the columns and values ​​to be inserted. DELETE statement: deletes rows with specified conditions.

Modify data in SQL

In SQL (Structured Query Language), there are several ways to Modify data in the database:

UPDATE statement:

The UPDATE statement is used to modify data in an existing table. The syntax is as follows:

<code class="sql">UPDATE table_name
SET column_name = new_value
WHERE condition;</code>

• table_name: The name of the table to update the data.
• column_name: The name of the column to be updated.
• new_value: The new value to be set.
• WHERE condition: Specify the condition of the row to be updated.

Example:

Update the "address" column in the table named "customers" and update the address of "John Doe" to "123 Main Street ":

<code class="sql">UPDATE customers
SET address = '123 Main Street'
WHERE name = 'John Doe';</code>

INSERT statement:

The INSERT statement is used to insert new rows into a table. The syntax is as follows:

<code class="sql">INSERT INTO table_name (column1, column2, ...)
VALUES (value1, value2, ...);</code>

• table_name: The name of the table to insert data into.
• column1, column2, ...: The column name to insert data.
• value1, value2, ...: The value to be inserted.

Example:

Insert a new row into the table named "orders":

<code class="sql">INSERT INTO orders (customer_id, product_id, quantity)
VALUES (1, 5, 2);</code>

DELETE statement:

DELETE statement is used to delete rows from a table. The syntax is as follows:

<code class="sql">DELETE FROM table_name
WHERE condition;</code>

• table_name: The name of the table from which data is to be deleted.
• condition: Specifies the condition for rows to be deleted.

Example:

Delete the row with product ID 10 from the table named "products":

<code class="sql">DELETE FROM products
WHERE product_id = 10;</code>

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