Function to update one column to another column in oracle

Oracle provides the UPDATE() function and a series of other column update functions, including NVL(), COALESCE(), GREATEST() and LEAST(), for updating one column to the value of another column. First determine the column to be updated, then find the column from which the updated value is to be obtained, and finally write the UPDATE() function to update the column.

Column update functions in Oracle

Oracle provides a series of functions that can easily update a column to the value of another column. The most commonly used function is the UPDATE() function.

UPDATE() function

UPDATE() function has the following syntax:

<code>UPDATE(expression, target_column, source_column)</code>

where:

• expression is the update condition.
• target_column is the column to be updated.
• source_column is the column from which the updated value is to be obtained.

How to use

To use the UPDATE() function, please follow these steps:

1. First, find out what you want Updated columns.
2. Then, determine the column from which you want to get the updated value.
3. Finally, write the UPDATE() function and use it to update the column.

Example

For example, suppose we have a table called "customers" that contains the "name" and "age" columns. To update the "name" column to the value of the "first_name" column, you can use the following query:

<code>UPDATE customers
SET name = first_name;</code>

Now, the "name" column will contain the value from the "first_name" column.

Other column update functions

In addition to the UPDATE() function, Oracle also provides other column update functions, including:

• NVL() function: Get non-null value.
• COALESCE() function : Get the first non-null value.
• GREATEST() function : Get the maximum value.
• LEAST() function : Get the minimum value.

Choosing which function to use depends on specific requirements.

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