how to insert current datetime in postgresql insert query

Okay, let's dive into how to insert the current date and time into a PostgreSQL `INSERT` query, covering different methods, considerations, and best practices.

**Understanding PostgreSQL's Date/Time Functions**

PostgreSQL provides several built-in functions that are crucial for working with date and time. The most relevant ones for our task are:

* **`NOW()`**: Returns the current transaction start time. This means that within a single transaction, multiple calls to `NOW()` will return the *same* timestamp. It's a stable and reliable value for transaction-consistent behavior.

* **`CURRENT_TIMESTAMP`**: An SQL standard alias for `NOW()`. It behaves identically to `NOW()`.

* **`LOCALTIMESTAMP`**: Returns the current date and time at the current local time.

* **`CURRENT_DATE`**: Returns the current date (without time).

* **`CURRENT_TIME`**: Returns the current time (without date).

* **`clock_timestamp()`**: Returns the actual current time. This is *not* transaction-safe and may give different results even within the same transaction if called repeatedly. Generally, `NOW()` or `CURRENT_TIMESTAMP` are preferred for database operations.

**Basic Insertion with `NOW()` or `CURRENT_TIMESTAMP`**

The simplest and most common way to insert the current date/time is to use `NOW()` or `CURRENT_TIMESTAMP` directly in your `INSERT` statement.

In this example:

1. We create a table `my_table` with a `created_at` and `updated_at` column, both of type `TIMESTAMP WITHOUT TIME ZONE`. This data type stores the date and time but without any specific timezone information. (More on timezones later.)
2. We use the `INSERT` statement, providing values for the `data`, `created_at`, and `updated_at` columns.
3. We use `NOW()` (or `CURRENT_TIMESTAMP`) as the value for both `created_at` and `updated_at`, effectively setting them to the current transaction start time.
4. We retrieve data from the table to verify that the `created_at` and `updated_at` columns hav ...

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