The Complete Guide to INSERT INTO Statement in SQL Server

The INSERT INTO statement is one of the most fundamental and frequently used SQL commands. It allows you to add new records to a table in SQL Server. Whether you’re inserting a single row or thousands of rows at once, understanding how to use the INSERT INTO statement effectively is essential for database management.

In this guide, we’ll cover everything you need to know about the INSERT INTO statement, from basic syntax to advanced techniques for inserting multiple records. Let’s dive in!

What is the INSERT INTO Statement?

The INSERT INTO statement is used to add new rows of data to a table in SQL Server. It allows you to specify:

• The table name where the data will be inserted.
• The columns you want to populate.
• The values to be inserted into those columns.

Basic Syntax of INSERT INTO

The basic syntax for the INSERT INTO statement is as follows:

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

Here’s what each part of the syntax means:

• table_name: The name of the table where you want to insert data.
• column1, column2, column3, ...: The columns in the table where you want to insert data. These are optional if you’re inserting values into all columns.
• value1, value2, value3, ...: The actual values you want to insert into the specified columns.

Example: Inserting a Single Record

Let’s say you have a table named Employees with the following columns:

• EmployeeID (an integer, unique for each employee)
• FirstName (a string, the employee’s first name)
• LastName (a string, the employee’s last name)

To insert a new employee into this table, you would use the following SQL statement:

INSERT INTO Employees (EmployeeID, FirstName, LastName)
VALUES (1, 'John', 'Doe');

In this example:

• We’re inserting a new row into the Employees table.
• The EmployeeID is set to 1, the FirstName is 'John', and the LastName is 'Doe'.

Inserting Multiple Records at Once

SQL Server allows you to insert multiple records in a single INSERT INTO statement. This is especially useful when you need to add several rows of data efficiently. To do this, you simply separate each set of values with a comma.

For example, let’s add three more employees to the Employees table:

INSERT INTO Employees (EmployeeID, FirstName, LastName)
VALUES 
(2, 'Jane', 'Smith'),
(3, 'Michael', 'Johnson'),
(4, 'Emily', 'Davis');

Here’s what’s happening:

• Three new rows are being added to the Employees table.
• Each set of values corresponds to a new employee:
  • EmployeeID 2, FirstName 'Jane', LastName 'Smith'
  • EmployeeID 3, FirstName 'Michael', LastName 'Johnson'
  • EmployeeID 4, FirstName 'Emily', LastName 'Davis'

Inserting Data into Specific Columns

Sometimes, you may not need to insert data into every column in a table. For example, if a column allows NULL values or has a default value defined, you can omit it from the INSERT INTO statement. Let’s look at an example:

INSERT INTO Employees (FirstName, LastName)
VALUES ('Sarah', 'Williams');

In this case:

• We’re only inserting data into the FirstName and LastName columns.
• The EmployeeID column is omitted. If this column is set to auto-increment or has a default value, SQL Server will handle it automatically.

Advanced Techniques for Inserting Multiple Records

If you’re working with large datasets or need to insert thousands of records at once, there are more efficient methods than using the basic INSERT INTO statement. Let’s explore some advanced techniques.

1. Using BULK INSERT

The BULK INSERT command is designed for inserting large volumes of data from a file into a table. It’s much faster than inserting rows one by one. Here’s an example:

BULK INSERT Employees
FROM 'C:\data\employees.csv'
WITH (FIELDTERMINATOR = ',', ROWTERMINATOR = '\n');

In this example:

• Data is being imported from a CSV file located at C:\data\employees.csv.
• The FIELDTERMINATOR specifies the delimiter between columns (e.g., a comma).
• The ROWTERMINATOR specifies the end of each row (e.g., a newline character).

2. Inserting Data from Another Table

You can also use the INSERT INTO SELECT statement to insert data from one table into another. This is useful for copying or transferring data. For example:

INSERT INTO NewEmployees (EmployeeID, FirstName, LastName)
SELECT EmployeeID, FirstName, LastName
FROM Employees
WHERE EmployeeID > 5;

In this example:

• Data is being copied from the Employees table to the NewEmployees table.
• Only employees with an EmployeeID greater than 5 are selected for insertion.

3. Using Transactions for Data Integrity

When inserting multiple records, it’s a good practice to use transactions to ensure data integrity. If any error occurs during the insert process, the transaction can be rolled back to maintain consistency. Here’s an example:

BEGIN TRANSACTION;

INSERT INTO Employees (EmployeeID, FirstName, LastName)
VALUES 
(5, 'David', 'Brown'),
(6, 'Laura', 'Wilson');

-- Check for errors
IF @@ERROR > 0
BEGIN
ROLLBACK TRANSACTION;
PRINT 'Error occurred. Transaction rolled back.';
END
ELSE
BEGIN
COMMIT TRANSACTION;
PRINT 'Transaction committed successfully.';
END

FAQs About the INSERT INTO Statement

INSERT INTO Employees
VALUES (5, 'David', 'Brown');

INSERT INTO Employees (EmployeeID, FirstName, LastName)
VALUES (6, 'Anna', NULL);

INSERT INTO BackupEmployees
SELECT * FROM Employees;

Conclusion

The INSERT INTO statement is a powerful and essential tool in SQL Server for adding new data to your tables. Whether you’re inserting a single record, multiple records, or handling large datasets, understanding how to use this statement effectively is crucial for managing your database.

By following the examples, techniques, and best practices provided in this guide, you’ll be able to confidently insert data into your tables while avoiding common pitfalls. Happy coding!