sql insert multiple rows from select with code examples

SQL is a powerful database language that provides numerous ways to work with data. One of the most useful features built into SQL is the ability to insert multiple rows of data from a SELECT statement. This feature comes in handy when there is a need to copy data from one table into another. There are many variations of the SQL INSERT statement, and in this article, we will focus on the particular use case of inserting multiple rows from a SELECT statement, with code examples.

The SQL INSERT INTO Statement

The SQL INSERT INTO statement is used to insert new records into a table. The basic syntax for the SQL INSERT INTO statement is as follows:

INSERT INTO table_name (column1, column2, column3, ...)
VALUES (value1, value2, value3, ...);

In this statement, we specify the name of the table we want to insert data into. Following this, we specify the column names we want to insert data into and then the values to be inserted in each column.

Inserting Multiple Rows from a SELECT Statement

To insert multiple rows of data from a SELECT statement, we can use the INSERT INTO statement along with a SELECT statement. The basic syntax for this is as follows:

INSERT INTO table_name (column1, column2, column3, ...)
SELECT column1, column2, column3, ...
FROM table_name_2
WHERE condition;

In this statement, we first specify the name of the table we want to insert data into and the columns we want to insert data into. Next, we specify a SELECT statement that retrieves the data we want to insert. We can use the WHERE clause to filter the data we want to insert.

Code Examples

Let us consider an example that demonstrates how to insert multiple rows of data from a SELECT statement in SQL. We will use two tables, Employee and Employee_Copy, where we want to copy the data from the Employee table into the Employee_Copy table.

Employee Table
+----+-------+--------+--------+
| ID | Name  | Salary | Gender |
+----+-------+--------+--------+
| 1  | John  | 50000  | Male   |
| 2  | Maria | 60000  | Female |
| 3  | Sam   | 55000  | Male   |
| 4  | Sue   | 62000  | Female |
+----+-------+--------+--------+

Employee_Copy Table
+----+-------+--------+--------+
| ID | Name  | Salary | Gender |
+----+-------+--------+--------+

We will use the following SQL INSERT INTO statement to copy the data from the Employee table into the Employee_Copy table:

INSERT INTO Employee_Copy (ID, Name, Salary, Gender)
SELECT ID, Name, Salary, Gender
FROM Employee;

In this INSERT INTO statement, we specify the columns we want to insert data into in the Employee_Copy table (ID, Name, Salary, Gender), followed by a SELECT statement that retrieves the data we want to insert from the Employee table.

After executing the above SQL statement, the Employee_Copy table will look like this:

Employee_Copy Table
+----+-------+--------+--------+
| ID | Name  | Salary | Gender |
+----+-------+--------+--------+
| 1  | John  | 50000  | Male   |
| 2  | Maria | 60000  | Female |
| 3  | Sam   | 55000  | Male   |
| 4  | Sue   | 62000  | Female |
+----+-------+--------+--------+

Conclusion

In conclusion, the ability to insert multiple rows of data from a SELECT statement is a powerful feature built into SQL that can be used to copy data from one table into another. The syntax for the SQL INSERT INTO statement is simple and straightforward, and it can be used to insert any number of rows of data into a table. With the help of code examples like the one in this article, anyone can easily master the art of inserting multiple rows of data from a SELECT statement in SQL.

I would be happy to provide more information about the topics we have previously discussed.

SQL Joins

SQL Joins are used to combine data from two or more tables based on a related column between them. There are four types of SQL Joins: INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL OUTER JOIN. Inner Join returns only the matching records between two tables, whereas Left and Right Join returns all records from one table and matching records from another table. Full Outer Join returns all records from both tables irrespective of whether there is a match or not.

SQL Subqueries

A subquery in SQL is a query that is nested within another SQL statement. The subquery can be used to retrieve data that will be used in the main query to filter or update data. Subqueries can be of two types: correlated and non-correlated subqueries. Correlated subqueries are dependent on the outer query, whereas non-correlated subqueries can be executed independently of the outer query.

SQL Views

SQL Views are virtual tables that are created from one or more tables in a database. Views are used to simplify complex queries, enhance security, and provide a consistent view of data to applications using the database. Views can be created using the CREATE VIEW statement and can be modified or dropped using the ALTER VIEW or DROP VIEW statements.

SQL Indexes

SQL Indexes are used to improve the performance of querying a table by providing a quick and efficient way to retrieve data from a table. Indexes are built on one or more columns of a table and help in quickly locating data based on the values in those columns. There are different types of indexes in SQL, including clustered and non-clustered indexes.

SQL Transactions

In SQL, a transaction is a sequence of SQL statements that need to be executed together to maintain the consistency of data in a database. The main property of a transaction is that it is atomic, which means that either all statements in a transaction are executed or none of them are executed. Transactions help in maintaining the integrity of data in a database by rolling back changes if there is an error during the execution of the transaction.

Overall, SQL is a powerful language that provides numerous ways to work with data and manage databases efficiently. Understanding SQL Joins, Subqueries, Views, Indexes, and Transactions are crucial to building robust databases and maintaining data integrity.

Popular questions

  1. What is the purpose of the SQL INSERT INTO statement?
    Answer: The SQL INSERT INTO statement is used to insert new records into a table.

  2. What is the syntax for inserting multiple rows from a SELECT statement in SQL?
    Answer: The syntax for inserting multiple rows from a SELECT statement in SQL is:

INSERT INTO table_name (column1, column2, column3, ...)
SELECT column1, column2, column3, ...
FROM table_name_2
WHERE condition;
  1. What is the purpose of the WHERE clause in the SQL INSERT INTO statement for inserting multiple rows from a SELECT statement?
    Answer: The WHERE clause in the SQL INSERT INTO statement for inserting multiple rows from a SELECT statement is used to filter the data that is selected from the source table.

  2. What is the difference between INNER JOIN and LEFT JOIN in SQL?
    Answer: INNER JOIN in SQL returns only the matching records between two tables, whereas LEFT JOIN returns all records from the left table and matching records from the right table.

  3. What are SQL Views and how are they used?
    Answer: SQL Views are virtual tables that are created from one or more tables in a database. Views are used to simplify complex queries, enhance security, and provide a consistent view of data to applications using the database. Views can be created using the CREATE VIEW statement and can be modified or dropped using the ALTER VIEW or DROP VIEW statements.

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As an experienced software engineer, I have a strong background in the financial services industry. Throughout my career, I have honed my skills in a variety of areas, including public speaking, HTML, JavaScript, leadership, and React.js. My passion for software engineering stems from a desire to create innovative solutions that make a positive impact on the world. I hold a Bachelor of Technology in IT from Sri Ramakrishna Engineering College, which has provided me with a solid foundation in software engineering principles and practices. I am constantly seeking to expand my knowledge and stay up-to-date with the latest technologies in the field. In addition to my technical skills, I am a skilled public speaker and have a talent for presenting complex ideas in a clear and engaging manner. I believe that effective communication is essential to successful software engineering, and I strive to maintain open lines of communication with my team and clients.
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