Looker Studio calculated field – Older date from a date field

The Looker Studio (ex Google Data Studio) calculated field below returns the older date from a date dimension. The min date in other words.

• Explanations of the formula
  • Get the older date of the date field using MIN function
  • Use LEFT_TEXT to extract the date part of the date time
  • Parse the text to cast it as a date using PARSE_DATE function when it is a unaggregated dimension
  • If you need a standalone field, without blending, it is easier to create a calculated field as an aggregated metric, using only MIN function (second formula below)

• Input
  • Any date type dimension
• Output
  • The older date
• Used functions
  • MIN
  • LEFT_TEXT
  • PARSE_DATE

Older date as a dimension 

PARSE_DATE("%Y/%m/%d",LEFT_TEXT(MIN(Date),10))

Older date as an aggregated metric 

MIN(Date)