Statements to modify table data in sql

There are two statements in SQL that modify table data: UPDATE statement: used to update specified row data, the syntax is UPDATE table_name SET column = value WHERE condition;. DELETE statement: used to delete specified rows, the syntax is DELETE FROM table_name WHERE condition;.

SQL statement to modify table data

In SQL, there are two main statements to modify table data:

1. UPDATE statement

Purpose: Update the data of the specified row in the table.

Syntax:

<code class="sql">UPDATE table_name
SET column1 = value1, column2 = value2, ...
WHERE condition;</code>

Example: Update the salary of the employee named "John Smith" in the table "employees":

<code class="sql">UPDATE employees
SET salary = 50000
WHERE name = 'John Smith';</code>

2. DELETE statement

Purpose: Delete the specified row from the table.

Syntax:

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

Example: Delete the customer with ID 10 from the table "customers":

<code class="sql">DELETE FROM customers
WHERE id = 10;</code>

Note:

• These statements will permanently modify data in the database, so please check carefully before use.
• Conditional clauses are very important for selecting rows to modify or delete. Without a conditional clause, all rows in the entire table will be modified or deleted.
• Multiple modification or delete operations can be combined into a single transaction to ensure atomicity.

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