PostgreSQL - Import CSV File Into Table

To import data from a CSV (Comma Separated Values) file into a PostgreSQL table, you can use the COPY command. Before you begin, make sure:

The PostgreSQL user has the necessary permissions to read the file.
The structure of the CSV file matches the table's structure (unless you're using column-specific imports).
The PostgreSQL server has access to the file's location.

Basic Syntax:

COPY table_name FROM '/path/to/your/file.csv' DELIMITER ',' CSV HEADER;

table_name: The name of the table you want to import data into.
/path/to/your/file.csv: The path to your CSV file.
DELIMITER ',': Specifies that the values in the CSV are separated by commas.
CSV HEADER: Indicates that the first row of the CSV file contains column headers.

Example:

Suppose you have a table called employees and a CSV file (employees.csv) with the following content:

id,first_name,last_name,email
1,John,Doe,john.doe@example.com
2,Jane,Smith,jane.smith@example.com

To import the CSV into the employees table:

COPY employees FROM '/path/to/employees.csv' DELIMITER ',' CSV HEADER;

Importing Data Using `psql`:

If you're using the psql command-line client, you can utilize the \COPY command which allows client-side files to be loaded, sidestepping permission issues with server-side files:

\COPY table_name FROM '/path/on/your/local/machine.csv' DELIMITER ',' CSV HEADER;

Tips:

If there's a mismatch between the CSV columns and the table's columns, you can specify which columns to import:
```
COPY table_name(column1, column2, column3) FROM '/path/to/file.csv' DELIMITER ',' CSV HEADER;
```
Ensure the CSV file's encoding matches what PostgreSQL expects. If your CSV is in a different encoding, you may need to convert it first or specify the encoding using the ENCODING option.
Be cautious about special characters or newlines within the data. If these are not correctly escaped in the CSV, they could cause errors during import.
Ensure the data types in the CSV match the columns of the table. If there's a type mismatch, the import will fail.

Always make a backup of your data or try the import first on a test environment, especially if you're working on a production database.

PostgreSQL import CSV into table:
- Description: Basic import of CSV data into a PostgreSQL table.
- Code:
```
COPY your_table FROM '/path/to/your/file.csv' DELIMITER ',' CSV HEADER;
```
How to load data from CSV file to PostgreSQL table:
- Description: Load CSV data into a PostgreSQL table.
- Code:
```
COPY your_table FROM '/path/to/your/file.csv' DELIMITER ',' CSV HEADER;
```
Using COPY command to import CSV in PostgreSQL:
- Description: Employ the COPY command for CSV import.
- Code:
```
COPY your_table FROM '/path/to/your/file.csv' DELIMITER ',' CSV HEADER;
```

Importing data from CSV using psql in PostgreSQL:

Description: Use the psql command-line tool for CSV import.

Code:

psql -h your_host -d your_database -U your_user -c "\COPY your_table FROM '/path/to/your/file.csv' DELIMITER ',' CSV HEADER"

Import CSV with header into PostgreSQL table:
- Description: Import CSV data with a header row.
- Code:
```
COPY your_table FROM '/path/to/your/file.csv' DELIMITER ',' CSV HEADER;
```
Loading CSV data into PostgreSQL with COPY FROM:
- Description: Use the COPY FROM command for CSV import.
- Code:
```
COPY your_table FROM '/path/to/your/file.csv' DELIMITER ',' CSV HEADER;
```
Importing large CSV files in PostgreSQL efficiently:
- Description: Optimize the import process for large CSV files.
- Code:
```
COPY your_table FROM '/path/to/your/large_file.csv' DELIMITER ',' CSV HEADER;
```
Handling CSV delimiters in PostgreSQL import:
- Description: Adjust delimiters during CSV import.
- Code:
```
COPY your_table FROM '/path/to/your/file.csv' DELIMITER ';' CSV HEADER;
```
Importing data with different CSV encoding in PostgreSQL:
- Description: Handle CSV files with various encodings.
- Code:
```
COPY your_table FROM '/path/to/your/file.csv' DELIMITER ',' CSV HEADER ENCODING 'UTF8';
```
Importing CSV with NULL values into PostgreSQL:
- Description: Handle NULL values during CSV import.
- Code:
```
COPY your_table FROM '/path/to/your/file.csv' DELIMITER ',' CSV NULL 'NA' HEADER;
```
Importing specific columns from CSV into PostgreSQL table:
- Description: Selectively import specific columns from CSV.
- Code:
```
COPY your_table(column1, column2) FROM '/path/to/your/file.csv' DELIMITER ',' CSV HEADER;
```
Importing CSV data with timestamp format in PostgreSQL:
- Description: Handle timestamps during CSV import.
- Code:
```
COPY your_table FROM '/path/to/your/file.csv' DELIMITER ',' CSV HEADER DATEFORMAT 'YYYY-MM-DD HH:MI:SS';
```
Importing CSV into temporary table in PostgreSQL:
- Description: Import CSV data into a temporary table.
- Code:
```
COPY temp_table FROM '/path/to/your/file.csv' DELIMITER ',' CSV HEADER;
```

Importing CSV from a remote server into PostgreSQL:

Description: Import CSV data from a remote server.