Migrating from one custom field type to another

Have you been using JIRA for more than a year, or are you a power user of JIRA? That is, have you performed huge customizations, created numerous plugins, used lot of use cases, and so on? Then it is very likely that you have come across this scenario. You want to move the values from an old custom field to a new field.

JIRA doesn't have a standard way of doing this, but you can achieve this to an extent by modifying the JIRA database. However even with SQL, there are some restrictions for doing this.

The first and most important thing to check is that both the fields are compatible. You can't move the values from a text field to a number field without extra checks and validations. If there is a value such as 1234a stored in one of the issues, it can't be stored as a number field as it is not a valid number. Another example is converting a multiline text field to a single-line text field. It is not possible, as the large value in a multiline...