Convert column integer values into date expressions

To convert column values representing dates in YYYYMMDD format into standard date expressions in PHP, you can use the DateTime class.

Here is an example:

Example of converting column integer values into date expressions in PHP

<?php

$column_values = ['19700101', '19700112', '19700424', '19720302', '19740529'];

foreach ($column_values as $value) {
  $date = DateTime::createFromFormat('Ymd', $value);
  echo $date->format('Y-m-d') . "\n";
}

This will output the following:

1970-01-01
1970-01-12
1970-04-24
1972-03-02
1974-05-29

In the example above, DateTime::createFromFormat('Ymd', $value) parses each string value into a DateTime object. The format('Y-m-d') method then converts that object into a standardized YYYY-MM-DD string.

Note that DateTime::createFromFormat returns false if the input string does not match the specified format. You should verify the result is a valid object before calling format() to prevent errors.