The column type is bigint and the values are

20211123
20220125

How can I change it to date:

2021-11-23
2022-01-25

CodePudding user response：

Use string functions to extract the characters, they'll automatically convert the number to a string.

SELECT CAST(CONCAT_WS('-', LEFT(colname, 4), SUBSTR(colname, 5, 2), RIGHT(colname, 2)) 
            AS DATE) AS date
FROM yourTable