Updating Data in SQL-Server

Updating data in SQL Server 2019 is a critical task, and Transact-SQL (T-SQL) provides a powerful and flexible set of commands to carry out this operation. The `UPDATE` statement is used to modify existing data in a table, and it can be precisely configured to update specific columns based on certain conditions.

• Syntax for Updating Specific Columns

  UPDATE [table_name]
  SET [column_name1] = [value1], [column_name2] = [value2], ...
  WHERE [condition];
  

  • table_name: The name of the table containing the data you want to update.
  • column_name1, column_name2, ...: The names of the columns that you want to update.
  • value1, value2, ...: The new values that you want to set for the specified columns.
  • condition: A condition that specifies which rows should be updated. Only the rows that satisfy this condition will be updated.

1. Connect to the Database: Use SQL Server Management Studio (SSMS) or any other preferred SQL client to connect to your SQL Server instance.
2. Open a New Query Window: Once connected, open a new query window to write your T-SQL commands.
3. Write the UPDATE Statement: In the query window, write your `UPDATE` statement, specifying the table name, the columns you want to update, their new values, and the condition to identify which rows should be updated.
4. Execute the Statement: After writing the `UPDATE` statement, execute it. Make sure to review your statement carefully before executing to avoid updating unintended rows.
5. Verify the Update: After executing the `UPDATE` statement, it is a good practice to verify that the data has been updated correctly. You can do this by executing a `SELECT` statement to retrieve the updated rows and inspect their values.

Example: Suppose you have a table named `Employees` with columns `EmployeeID`, `FirstName`, `LastName`, and `Salary`. To update the `Salary` of an employee with `EmployeeID` 101, you can use the following T-SQL command:

UPDATE Employees
SET Salary = 60000
WHERE EmployeeID = 101;

This statement updates the `Salary` column to 60000 for the employee with `EmployeeID` 101.
Updating specific columns in a table is a common and crucial operation in SQL Server. The `UPDATE` statement in Transact-SQL provides a robust way to perform these updates, ensuring that you can modify your data accurately and efficiently. Always ensure to include a specific `WHERE` clause to prevent unintentional updates to other rows in the table. Additionally, it is highly recommended to back up your data or test your update commands on a staging environment before executing them on a production database to ensure data integrity and consistency.
To update data in a table, you use the UPDATE Transact-SQL statement. When updating data, you must specify the names of the specific columns that you are going to update.
The UPDATE statement uses the following general syntax:

To increase an integer value in SQL Server, you can use the `UPDATE` statement along with the `SET` clause. Here’s a basic example:

UPDATE table_name
SET column_name = column_name + 1
WHERE condition;

This statement increases the value in `column_name` by 1 for rows that match the specified `condition`. You can adjust the `+ 1` to increase the value by any desired amount.

IDENTITY Column: Unlike an INSERT statement, an UPDATE statement cannot update the values of an IDENTITY column. In the next lesson, you will learn about the DELETE statement.