How to Copy Rows from One Table to Another in SQL?

In SQL, copying rows from one table to another is a common operation that simplifies data migration and duplication tasks. Whether creating backup tables, transferring data for analysis, or setting up a new schema, the ability to efficiently replicate data across tables is invaluable. This operation not only saves time but also reduces manual errors, making database management more streamlined and efficient.

In this article. we will explain how to copy rows from one table to another in SQL using the INSERT INTO SELECT query. By following these examples, we can learn the step-by-step process and its practical applications.

Copy Rows from One Table to Another

We will follow the below steps to Implement How to Copy rows from one table to another table in SQL. The process involves creating a source table with data, a target table, and then using the INSERT INTO SELECT query to copy the data efficiently.

Step 1: Create the Source Table (EMPLOYEE)

The first step involves creating a source table named EMPLOYEE and inserting sample data into it. The EMPLOYEE table contains columns for employee name, gender, department, contact number, and city. Sample data is inserted into the table using the INSERT INTO statement.

Query:

CREATE TABLE EMPLOYEE
(
EMPNAME VARCHAR(25),
GENDER VARCHAR(6),
DEPT VARCHAR(20),
CONTACTNO BIGINT NOT NULL,
CITY VARCHAR(15)
); 

INSERT INTO EMPLOYEE
VALUES ('VISHAL','MALE','SALES',9193458625,'GHAZIABAD'),
('DIVYA','FEMALE','MANAGER',7352158944,'BAREILLY'),
('REKHA','FEMALE','IT',7830246946,'KOLKATA'),
('RAHUL','MALE','MARKETING',7906334516,'MEERUT'),
('SANJAY','MALE','SALES',9149335694,'MORADABAD'),
('RAJKUMAR','MALE','MANAGER',9675274391,'BENGALURU'),
('RAJSHREE','FEMALE','SALES',9193458625,'VODODARA'),
('HAIM','MALE','IT',7088573213,'SAMBHAL'),
('RAKESH','MALE','MARKETING',9645956441,'BOKARO'),
('MOHINI','FEMALE','SALES',9147844694,'Delhi'); 

 SELECT * FROM EMPLOYEE; 

Output

Step 2: Create the Target Table (ATTENDANCE)

Next, we will Create a target table name ATTENDANCE. In this table we will not Insert record manually because the same data exist in another table EMPLOYEE therefore, we will copy data from EMPLOYEE table to ATTENDANCE Table. The INSERT INTO SELECT query is used for this operation.

Query:

CREATE TABLE ATTENDANCE
( EMPNAME VARCHAR(25),
GENDER VARCHAR(6),
DEPT VARCHAR(20),
ATTENDATE DATE DEFAULT GETDATE()
); 

INSERT INTO ATTENDANCE (EMPNAME,GENDER,DEPT)
SELECT EMPNAME,GENDER,DEPT FROM EMPLOYEE; 

SELECT * FROM ATTENDANCE;

Output

Explanation

• The ATTENDANCE table has a similar structure to the EMPLOYEE table, but includes an additional column ATTENDATE with a default value of the current date.
  
• The INSERT INTO SELECT query copies specific columns (EMPNAME, GENDER, DEPT) from the EMPLOYEE table into the ATTENDANCE table.

Key Points

1. INSERT INTO SELECT: Combines the INSERT and SELECT statements to copy data from one table to another.
   
2. Default Values: Columns with default values, like ATTENDATE, automatically populate when not explicitly included in the query.
   
3. Efficiency: The method eliminates the need to manually insert data, saving time and ensuring accuracy.

Conclusion

Copying rows from one table to another in SQL is a straightforward and powerful technique for data management. By mastering the INSERT INTO SELECT query, we can efficiently duplicate data, transfer information between environments, or populate backup tables. This method eliminates manual effort, ensures accuracy, and streamlines the data replication process. Understanding the structure and compatibility of tables ensures a seamless copying process, enhancing both SQL proficiency and database management efficiency.