> This page location: PostgreSQL C# > Import Data from CSV using C# > Full Neon documentation index: https://neon.com/docs/llms.txt # PostgreSQL C#: Importing Data from a CSV File into a Table **Info:** Importing CSV data into PostgreSQL with C# and Npgsql works the same against any Postgres database, so the patterns shown here carry over wherever you run Postgres. If you're an enterprise looking for managed Postgres built for the AI era, [Lakebase](https://www.databricks.com/product/lakebase) delivers high performance, strong security, and native integration with the Lakehouse. If you're a developer or startup that needs to ship and scale quickly, [Neon](https://neon.com) gives you the fastest path to production Postgres. **Summary**: in this tutorial, you will learn how to import data from a CSV file into a table in PostgreSQL using C#. This tutorial begins where the [Inserting data into a table in PostgreSQL tutoria](https://neon.com/postgresql/csharp/postgresql-csharp-insert)l left off. ## How to import a CSV file into the PostgreSQL database using C# To import data from a CSV file into a table in PostgreSQL from a C# program, you follow these steps: - First, read data from the CSV file into a list of records. - Second, iterate over the list and [insert each record into the table](https://neon.com/postgresql/csharp/postgresql-csharp-insert). ## Importing a CSV file into PostgreSQL The following program illustrates how to import data from `students.csv` file into the `students` table in the `elearning` database: ```cs using CsvHelper; using System.Globalization; using Npgsql; namespace ELearning; public record Student(string FirstName, string LastName, string Email, DateOnly RegistrationDate); public class Program { public static IEnumerable ReadStudentsFromCSV(string filePath) { using var reader = new StreamReader(filePath); using var csv = new CsvReader(reader, CultureInfo.InvariantCulture); // Skip header of the csv file csv.Read(); // Read the header of the csv file to map to fields csv.ReadHeader(); while (csv.Read()) { var firstName = csv.GetField("Firstname"); var lastName = csv.GetField("Lastname"); var email = csv.GetField("Email"); var registrationDate = csv.GetField("RegistrationDate"); yield return new Student(firstName, lastName, email, registrationDate); } } public static async Task Main() { var csvFilePath = @"c:\db\students.csv"; var sql = @"INSERT INTO students(first_name, last_name, email, registration_date) " + "VALUES(@first_name,@last_name,@email,@registration_date)"; string connectionString = ConfigurationHelper.GetConnectionString("DefaultConnection"); try { // Create a new data source await using var dataSource = NpgsqlDataSource.Create(connectionString); // Insert lines of CSV into the students table foreach (var student in ReadStudentsFromCSV(csvFilePath)) { await using var cmd = dataSource.CreateCommand(sql); cmd.Parameters.AddWithValue("@first_name", student.FirstName); cmd.Parameters.AddWithValue("@last_name", student.LastName); cmd.Parameters.AddWithValue("@email", student.Email); cmd.Parameters.AddWithValue("@registration_date", student.RegistrationDate); await cmd.ExecuteNonQueryAsync(); } } catch (NpgSQLException ex) { Console.WriteLine(ex.Message); } } } ``` In this program, we use an external package for reading a CSV file called `CsvHelper`. You can install the `CsvHelper` package by running the following command in the Package Manager Console: ```cs Install-Package CsvHelper ``` To learn more details on reading data from a CSV file using the `CsvHelper` package, check out the tutorial on [how to read a CSV file in C# using the CsvHelper package](https://www.csharptutorial.net/csharp-file/csharp-read-csv-file/). Note that you can [download the students.csv file](https://neon.com/postgresqltutorial/students.csv) from here. Let's discuss how the program works. ### Declaring Student record Define a `Student` [record](https://www.csharptutorial.net/csharp-tutorial/csharp-record/) that includes the following fields: `FirstName`, `LastName`, `Email`, and `RegistrationDate`: ```cs public record Student(string FirstName, string LastName, string Email, DateOnly RegistrationDate); ``` ### Defining ReadStudentsFromCSV() method The `ReadStudentsFromCSV()` method reads data from a CSV file specified by a `filePath` and returns an enumerable sequence of `Student` records. ```cs public static IEnumerable ReadStudentsFromCSV(string filePath) { using var reader = new StreamReader(filePath); using var csv = new CsvReader(reader, CultureInfo.InvariantCulture); // Skip header of the csv file csv.Read(); // Read the header of the csv file to map to fields csv.ReadHeader(); while (csv.Read()) { var firstName = csv.GetField("Firstname"); var lastName = csv.GetField("Lastname"); var email = csv.GetField("Email"); var registrationDate = csv.GetField("RegistrationDate"); yield return new Student(firstName, lastName, email, registrationDate); } } ``` How it works. First, create a `StreamReader` from the CSV file specified by the `filePath`. The `using` statement ensures that the `StreamReader` is properly closed: ```cs using var reader = new StreamReader(filePath); ``` Second, create a `CsvReader` to parse the CSV data. The `CultureInfo.InvariantCulture` ensures consistent parsing across different locales: ```cs using var csv = new CsvReader(reader, CultureInfo.InvariantCulture); ``` Third, read the heading line from a CSV file, which advances the reader to the next line in the CSV file: ```cs csv.Read(); ``` Fourth, read the header row of the CSV file to map the column names to fields: ```cs csv.ReadHeader(); ``` Fifth, start a loop that iterates over each line in the CSV file. The `Read()` method reads the next line from the CSV file and returns true if successful, or false if there are no more lines: ```cs while (csv.Read()) ``` Sixth, retrieve the values of the columns of the CSV file: ```cs var firstName = csv.GetField("Firstname"); var lastName = csv.GetField("Lastname"); var email = csv.GetField("Email"); var registrationDate = csv.GetField("RegistrationDate"); ``` Finally, return a new `Student` record for each row in the CSV file. The `yield return` returns multiple `Student` records iteratively without loading them all in memory: ```cs yield return new Student(firstName, lastName, email, registrationDate); ``` ### Defining Main() method First, declare a variable `csvFilePath` and initialize it with the path to the CSV file: ```cs var csvFilePath = @"c:\db\students.csv"; ``` Next, declare a variable `sql` and initialize it with an SQL `INSERT` statement: ```cs var sql = @"INSERT INTO students(first_name, last_name, email, registration_date) " + "VALUES(@first_name,@last_name,@email,@registration_date)"; ``` Then, get a connection string from the `appsettings.json` file using the `ConfigurationHelper` class: ```cs var connectionString = ConfigurationHelper.GetConnectionString("DefaultConnection"); ``` After that, create a data source that represents the PostgreSQL database: ```cs await using var dataSource = NpgsqlDataSource.Create(connectionString); ``` Finally, iterate over each `Student` record list returned by the `ReadStudentsFromCSV()` method and execute the `INSERT` statement to insert the new row into the `students` table: ```cs foreach(var student in ReadStudentsFromCSV(csvFilePath)) { await using var cmd = dataSource.CreateCommand(sql); cmd.Parameters.AddWithValue("@first_name", student.FirstName); cmd.Parameters.AddWithValue("@last_name", student.LastName); cmd.Parameters.AddWithValue("@email", student.Email); cmd.Parameters.AddWithValue("@registration_date", student.RegistrationDate); await cmd.ExecuteNonQueryAsync(); } ``` ## Verify the inserts First, open a terminal and connect to the `elearning` database using the `ed` user: ```bash psql -U ed -d elearning ``` It'll prompt you to enter a password for the `ed` user. Input the valid password and press Enter to connect to the PostgreSQL. Second, query data from the `students` table: ```sql SELECT * FROM students; ``` Output: ``` id | first_name | last_name | email | registration_date ----+------------+-----------+------------------------------+------------------- 1 | John | Doe | john.doe@example.com | 2024-05-20 2 | Emma | Smith | emma.smith@example.com | 2024-05-20 3 | Liam | Johnson | liam.johnson@example.com | 2024-05-20 4 | Olivia | Williams | olivia.williams@example.com | 2024-05-20 5 | Noah | Brown | noah.brown@example.com | 2024-05-15 6 | Ava | Jones | ava.jones@example.com | 2024-05-15 7 | William | Garcia | william.garcia@example.com | 2024-05-15 8 | Sophia | Miller | sophia.miller@example.com | 2024-05-10 9 | James | Davis | james.davis@example.com | 2024-05-10 10 | Isabella | Rodriguez | isabella.rodriguez@example.com | 2024-05-10 11 | Benjamin | Martinez | benjamin.martinez@example.com | 2024-05-10 (11 rows) ``` The output indicates that the program has successfully imported 10 rows from the `students.csv` file into the `students` table. ## Summary - Utilize the `CsvHelper` package to read data from a CSV file. - Call the `ExecuteNonQueryAsync()` method of the `NpgsqlCommand` object to execute an SQL `INSERT` statement to load data from a CSV file into a table in the SQLite database. --- ## Related docs (PostgreSQL C#) - [Connect to Database Using C#](https://neon.com/postgresql/csharp/csharp-connect) - [Call a Stored Procedure using C#](https://neon.com/postgresql/csharp/csharp-call-a-stored-procedure) - [Call PostgreSQL Functions using C#](https://neon.com/postgresql/csharp/csharp-call-postgresql-function) - [Connect to PostgreSQL using C#](https://neon.com/postgresql/csharp/csharp-connect) - [Create Tables using C#](https://neon.com/postgresql/csharp/csharp-create-table) - [Delete Data from a Table using C#](https://neon.com/postgresql/csharp/csharp-delete) - [Insert Data Into Tables using C#](https://neon.com/postgresql/csharp/csharp-insert) - [Select Data in a Table using C#](https://neon.com/postgresql/csharp/csharp-select) - [PostgreSQL Transactions in C#](https://neon.com/postgresql/csharp/csharp-transaction) - [Update Data in a Table in C#](https://neon.com/postgresql/csharp/csharp-update)