How to Copy Data From One Column to Another in the Same Table in SQL?

Efficiency in data manipulation is crucial while using Structured Query Language (SQL). To manage a wide range of tasks, including organizing, retrieving, updating, and deleting data, SQL provides a comprehensive set of instructions. It is common practice to copy data between columns in the same table. This operation is helpful when transferring or copying data for analysis or application needs.

We will learn how to copy data from one column to another inside the same column in this article. ⁤⁤ We will comprehend the primary idea as well as the syntax, importance, and examples to illustrate the topic.

Copying Data Within the Same Table

When data is copied from one column to another, the SQL Data Insertion requires that values for each column are updated in the same table with other columns’ values. Data transformation, redundancy, and calculation are common uses of this method. Maintaining data integrity, ensuring data consistency, and optimizing the use of data manipulation methods in a database are at the heart of this method.

Syntax:

The syntax for copying data from one column to another in SQL involves the UPDATE statement along with the appropriate column names. The syntax is as follows:

UPDATE table_name

SET to_column = from_column;

In this syntax:

• table_name: mentions the name of the table containing both columns.
• to_column: Represents the column where the data will be copied.
• from_column: Denotes the column from which data will be copied.

Significance of Copying Data Within SQL Tables

1. Formatting or changing data: When we need to transform or reformat data in one column, then copying the data into another column can be useful for such transformations. This helps maintain the integrity of the database by not changing the original data in the previous column.
2. Data Redundancy for Enhanced Recovery: Duplicating data within a table creates redundancy, a vital practice for backup and retrieval purposes. If the original data gets lost or corrupted then the redundant copy ensures data integrity and minimizes the risk of permanent information loss.
3. Derived Columns for Analysis: Data analysis often requires new calculations based on existing information. By copying a column, you can perform these calculations on the copy, essentially creating a new custom column with the desired values. This simplifies tasks like data analysis and reporting.

Examples of Copying Data Within the Same SQL Table

Example 1: Copying first names to last names in a table named students.

Suppose we have a table named students with columns ‘first_name‘ and ‘last_name‘. We want to copy the first names of students to their corresponding last names.

first_name	last_name
Rahul	NULL
Priya	NULL

We will use the query:

 UPDATE students
SET last_name = first_name;

Output:

first_name	last_name
Rahul	Rahul
Priya	Priya

Explanation: Here, the ‘first_name‘ column is successfully copied to the ‘last_name‘ column, resulting in both columns containing the same values.

Example 2: Calculating and storing discounted prices in the discounted_price column based on the price column in a table named products.

Suppose we have a table named products with columns ‘price’ and ‘discounted_price’. We want to calculate and store the discounted prices in the ‘discounted_price’ column.

price	discounted_price
100.00	NULL
50.00	NULL

We will use the query:

UPDATE products
SET discounted_price = price * 0.9;

Output:

price	discounted_price
100.00	90.00
50.00	45.00

Explanation: In this example, a 10% discount is applied to the ‘price‘ column, and the resulting discounted prices are stored in the ‘discounted_price‘ column. It’s useful for pre-calculating discounted prices to optimize query performance or simplify business logic.

Example 3: Copying math scores to science scores for specific students in a table named students.

Let’s consider a scenario where we have a table named students with columns ‘math_score‘ and ‘science_score‘. Now, suppose we want to copy the math score of a specific student to their science score.

student_id	math_score	science_score
101	85	NULL
102	90	NULL

We can use the query:

 UPDATE students
SET science_score = math_score
WHERE student_id = 101;

Output:

After executing the update statement, the data will be updated as follows:

student_id	math_score	science_score
101	101	85
102	90	NULL

Explanation: Here, the math score of the student with ‘student_id‘ 101 (85) is copied to their science score. As a result, the ‘science_score‘ column for this student now contains the same value as their ‘math_score‘ (85). The data for other students remains unaffected.

Conclusion

We learned how to copy data from one column to another in the same table using SQL. To accomplish this efficiently we can utilize the UPDATE command. It is crucial to ensure that the data types of both columns match to prevent any issues or complications when transferring the data. This procedure plays a role in data organization and record updates.