How to Update Data in a SQL Database Table

Updating data stored in a SQL database table is a common task when working with relational databases. To accomplish this, you can use the UPDATE command to modify specific rows of your table. However, it is crucial to include a WHERE clause to ensure that only the intended rows are updated.

Let’s take a closer look at the syntax and usage of the UPDATE command:

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UPDATE table_name
SET column_name1 = new_value1, column_name2 = new_value2, ...
WHERE condition;

In the above example, table_name refers to the name of the table you want to update. The SET keyword is followed by a list of column-value pairs that you want to modify. Each column is specified by its name, followed by the new value you want to assign.

The WHERE clause is what ensures that the update operation is applied only to specific rows. You need to provide a condition that determines which rows will be affected by the update. In the example above, the condition is typically expressed as a comparison between the column values and a specific value or a combination of logical operators.

Without a WHERE clause, the UPDATE command will modify all rows in the table, which is usually not desirable and can lead to unintended consequences.

Now, let’s apply this concept to a practical example:

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UPDATE people
SET age = 2
WHERE name = 'Roger';

In this example, we are updating the age column of the people table, specifically for the row where the name value is equal to ‘Roger’. Only the row that meets this condition will be modified.

By using the UPDATE command with a WHERE clause, you can selectively update specific data in your SQL database table, ensuring accuracy and control over the changes you make.

Tags: SQL, Database, Update, WHERE clause