DbMigration (ebean-annotation 6.15 API)

```
@Retention(RUNTIME)
@Target(FIELD)
@Repeatable(List.class)
public @interface DbMigration
```
Annotation to specify details for DDL & Migration-generation. (e.g. defaults/renames/...) This annotation is EXPERIMENTAL and may change.

Author:

Roland Praml, FOCONIS AG

Optional Element Summary

Optional Elements
Modifier and Type	Optional Element	Description
`Platform[]`	`platforms`	Specific platforms this migration change applies to.
`String[]`	`postAdd`	DdlScript that will be executed after the 'add' command.
`String[]`	`postAlter`	DdlScript that will be executed after the 'alter' command
`String[]`	`preAdd`	DdlScript that will be executed before the 'add' command
`String[]`	`preAlter`	DdlScripts that will be executed before the 'alter' command.

- Element Detail
  - preAlter
```
String[] preAlter
```
    DdlScripts that will be executed before the 'alter' command.
    You may write a custom update routine here. If you do not specify an SQL here, and this will alter the table to a non-null column, ebean will autogenerate a statement from default value like this:
    UPDATE table SET column = 'foo' WHERE column IS NULL
    Default:
    
    {}
- - postAlter
```
String[] postAlter
```
    DdlScript that will be executed after the 'alter' command
    
    Default:
    
    {}
- - preAdd
```
String[] preAdd
```
    DdlScript that will be executed before the 'add' command
    
    Default:
    
    {}
- - postAdd
```
String[] postAdd
```
    DdlScript that will be executed after the 'add' command. You may write certain update scripts here.
    
    Default:
    
    {}
- - platforms
```
Platform[] platforms
```
    Specific platforms this migration change applies to.
    
    Default:
    
    {}