How to Use “Insert Into Select” in SQL Server: A Comprehensive Guide for Dev

Welcome, Dev! In this article, we will discuss one of the most common and useful SQL Server commands – “Insert Into Select”. This command is used to insert data from one table into another table while also allowing us to filter the data. If you are new to SQL Server or just starting to learn SQL, this article is for you. We will explain the basics of “Insert Into Select” and provide detailed examples to help you fully understand how to use it. Let’s dive right in!

What is “Insert Into Select”?

The “Insert Into Select” statement is a SQL Server command that allows you to insert data from one table into another table. This command also lets you filter the data you want to insert into the new table. In other words, “Insert Into Select” copies data from one table and pastes it into another table based on specified conditions. It is a very powerful tool when it comes to manipulating data in databases.

Here is the basic syntax of the “Insert Into Select” statement:

Syntax
INSERT INTO new_table (column1, column2, column3, …) SELECT column1, column2, column3, … FROM old_table WHERE condition;

Explanation of Syntax:

• The “INSERT INTO” statement specifies the new table and columns where the data will be inserted.
• The “SELECT” statement specifies the old table and columns from where the data will be retrieved.
• The “WHERE” clause specifies a condition to filter the data from the old table.

In the next section, we will dive deeper into the “Insert Into Select” statement and provide practical examples to help you understand how to apply it in your SQL Server queries.

Practical Examples of “Insert Into Select” in SQL Server

To better understand how to use “Insert Into Select”, let’s take a look at some practical examples. In each of these examples, we will demonstrate how to use the “Insert Into Select” statement in a specific scenario. Make sure to follow along with the code examples and try them out on your own SQL Server database.

Example 1: Copying All Columns from One Table to Another

In this example, we will copy all the columns of the “employees” table to a new table called “employees_backup”. This is a simple example that demonstrates the basics of the “Insert Into Select” statement.

First, let’s create the “employees” table:

Table: employees
Column Data Type id int name varchar(50) department varchar(50) salary int

Now, let’s insert all the data from the “employees” table into the “employees_backup” table:

SQL Query
INSERT INTO employees_backup SELECT * FROM employees;

The above SQL query will copy all the columns and data from the “employees” table to the “employees_backup” table. The asterisk (*) symbol in the “SELECT” statement indicates that we want to select all the columns from the “employees” table.

Example 2: Copying Selected Columns and Filtered Data from One Table to Another

In this example, we will copy only the “name” and “salary” columns from the “employees” table to a new table called “employees_high_salary”. We will also filter the data to only include employees with a salary of more than $50,000.

First, let’s create the “employees” table:

Table: employees
Column Data Type id int name varchar(50) department varchar(50) salary int

Now, let’s insert the filtered data from the “employees” table into the “employees_high_salary” table:

SQL Query
INSERT INTO employees_high_salary (name, salary) SELECT name, salary FROM employees WHERE salary > 50000;

The above SQL query will copy only the “name” and “salary” columns from the “employees” table to the “employees_high_salary” table. The “WHERE” clause specifies that we only want to select employees with a salary of more than $50,000.

Example 3: Copying Data from Multiple Tables into One Table

In this example, we will copy data from two tables – “employees” and “departments” – into a new table called “employee_departments”. We will also join these two tables to get the data we need.

First, let’s create the “employees” table:

Table: employees
Column Data Type id int name varchar(50) department_id int salary int

Next, let’s create the “departments” table:

Table: departments
Column Data Type id int name varchar(50)

Now, let’s insert the relevant data from the “employees” and “departments” tables into the “employee_departments” table:

SQL Query
INSERT INTO employee_departments (employee_name, department_name) SELECT e.name, d.name FROM employees e INNER JOIN departments d ON e.department_id = d.id;

The above SQL query will copy the “name” column from the “employees” table and the “name” column from the “departments” table into the “employee_departments” table. We used the “INNER JOIN” statement to combine the two tables based on the “department_id” column from the “employees” table and the “id” column from the “departments” table.

FAQs

What is the difference between “Insert Into” and “Insert Into Select”?

The “Insert Into” statement is used to insert data into a table by manually specifying the values for each column. The “Insert Into Select” statement, on the other hand, allows you to insert data into a table from another table or tables. This can be useful when you want to copy or manipulate data from one table to another.

Can I use “Insert Into Select” to insert data into a table with a different schema?

Yes, you can use “Insert Into Select” to insert data into a table with a different schema as long as the columns match. If the columns do not match, you will need to specify which columns you want to insert data into and which columns you want to skip.

What happens if I use “Insert Into Select” on a table with an identity column?

If you use “Insert Into Select” on a table with an identity column, the identity values will be copied from the old table to the new table. This means that the new table will continue the identity values from where the old table left off. If you want to reset the identity values in the new table, you will need to use the “SET IDENTITY_INSERT” command.

Is “Insert Into Select” a safe operation?

Yes, “Insert Into Select” is a safe operation as long as you are careful when selecting the data to insert into the new table. You should always test your queries on a test database before running them on a production database. You should also make sure that you have proper backups in case anything goes wrong.

Can I use “Insert Into Select” to insert data into a temporary table?

Yes, you can use “Insert Into Select” to insert data into a temporary table. Temporary tables are created within the current session and are automatically dropped when the session ends. This can be useful when you need to manipulate data within a specific session without affecting other sessions or the original data.

Conclusion

That’s it for our comprehensive guide on “Insert Into Select” in SQL Server. We hope this article has provided you with a clear understanding of how to use this powerful command. “Insert Into Select” is a very useful tool when it comes to manipulating data in databases, and we encourage you to explore it further in your SQL Server queries. As always, make sure to test your queries on a test database and have proper backups in place. Thanks for reading!