UPDATE

The UPDATE statement in SQL Server is used to modify existing data in a table.

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Syntax:

UPDATE table_name
SET column1 = value1, column2 = value2, ...
WHERE condition;

• Explanation:
  • table_name: The table where the data is to be updated.
  • SET: Specifies the columns to update and their new values.
  • WHERE: Specifies the condition to identify the rows to be updated (optional but recommended to avoid updating all rows).

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Example:

• Update a single column:

UPDATE employees
SET age = 31
WHERE id = 1;

• Update multiple columns:

UPDATE employees
SET name = 'John Smith', age = 32
WHERE id = 1;

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Key Points:

1. WHERE clause is crucial to limit which rows are updated. Without it, all rows in the table will be updated.
2. The SET clause can update multiple columns in a single statement.
3. Ensure data integrity by checking conditions before updating to avoid accidental changes to all records.