Question

I have a table table_a with the column field_b which format is string.

In that field their is written e.g. 01/06/2012.

I need to change it to 2012-06-01

I cannot change fields type etc.

Answer 1

Most SQL engines have a substring() function. Use that together with concat() to create the new string:

(pseudocode)

update table_a set field_b=concat(substring(field_b, 6, 4), '-', substring(field_b, 3, 2), '-', substring(field_b, 0, 2))

Refer to your SQL server’s manual for details.