# How to insert csv data into postgreSQL

To specify the file in Postgres for the `COPY` command to copy the comma-separated data into the `users` table of the Postgres SQL, you need to use the `FROM` clause followed by the file path or the `STDIN` keyword.

If you want to copy data from a file, you can specify the file path in the `FROM` clause, like this:

### First standard way

```plaintext
COPY users FROM '/path/to/data.csv' WITH (FORMAT csv, DELIMITER ',', HEADER true);
```

In this example, we're copying data from the `/path/to/data.csv` file, which is a CSV file with a comma delimiter and a header row.

the "HEADER true" option specifies that the first row of the CSV file contains the column headers. If your CSV file does not contain headers, you should remove this option.

### Second STDIN way

If you want to copy data from the standard input (stdin), you can use the `STDIN` keyword, like this:

```plaintext
COPY users FROM STDIN WITH (FORMAT csv, DELIMITER ',', HEADER true);
```

In this example, we're copying data from the standard input (stdin) with the same format and delimiter options as before. You can then pipe data into the `STDIN` of the `COPY` command to insert data into the `users` table.

### To pipe the data from CSV using psql (Method 1)

To pipe data into the STDIN of the `COPY` command, you can use the command-line shell or another program that can send data to the standard input stream of a process. Here is an example using the command-line shell:

```plaintext
cat data.csv | psql -d dbname -c "COPY users FROM STDIN WITH DELIMITER as ','"
```

In this example, `data.csv` is a comma-separated values file containing the data you want to insert into the `users` table. The `cat` command outputs the contents of the file to the standard output stream, which is then piped to the `psql` command. The `-d` option specifies the name of the database to connect to, and the `-c` option specifies the SQL command to execute. The `COPY` command reads data from the standard input stream, and the `WITH DELIMITER as ','` option specifies the delimiter to use for parsing the data.

Note that you will need to have the necessary permissions to execute the `COPY` command and access the `users` table in the database.

### To pipe data from CSV (Method 2)

Assume that you have a CSV file named `users.csv` with the following data:

```plaintext
Alice,Smith,US,asmith,password123,asmith@example.com
Bob,Jones,UK,bjones,bob123,bjones@example.com
```

Here's how you can use the `COPY` command to insert this data into a `users` table in PostgreSQL:

1. First, create a `users` table in PostgreSQL with the appropriate columns:
    

```plaintext
CREATE TABLE users (
  firstname TEXT,
  lastname TEXT,
  country TEXT,
  username TEXT,
  password TEXT,
  email TEXT
);
```

1. Next, run the following command in the terminal to start the `psql` command-line interface and connect to your PostgreSQL database:
    

```plaintext
psql -U <username> -d <database_name>
```

Replace `<username>` and `<database_name>` with your PostgreSQL username and database name, respectively.

1. Once you are connected to your PostgreSQL database, run the following command to start the `COPY` command:
    

```plaintext
COPY users FROM stdin WITH DELIMITER as ','
```

1. After running the above command, you can start entering the data from your CSV file. Copy and paste the contents of the `users.csv` file into the terminal, making sure to separate each value with a comma (`,`) and to end each row with a newline (`\n`). The `COPY` command will continue to wait for more data until you signal the end of input by typing `\.\n`.
    

Here's an example of what you would copy and paste into the terminal:

```plaintext
Alice,Smith,US,asmith,password123,asmith@example.com
Bob,Jones,UK,bjones,bob123,bjones@example.com
\.
```

1. After pasting in the data and ending with `\.\n`, press Enter to execute the `COPY` command.
    

If everything goes well, the data from the `users.csv` file will be inserted into the `users` table in your PostgreSQL database. You can verify this by running a `SELECT` query on the `users` table:

```plaintext
SELECT * FROM users;
```

This should return the following output:

```plaintext
firstname | lastname | country | username |   password    |           email           
-----------+----------+---------+----------+---------------+--------------------------
 Alice     | Smith    | US      | asmith   | password123   | asmith@example.com
 Bob       | Jones    | UK      | bjones   | bob123        | bjones@example.com
(2 rows)
```