db2 modify column type

DB2 is so hard to use, also its documentation... Even such a simple operation, it takes me much time...

 

Generally, char->varchar, smallint->integer, you can just modify the column through this sql:

alter table [table name] alter column [column name] set data type [new type]

 

But, if new column type is not compatible with existing column type, you need to modify it as follows:

 

1. maybe need to export old column data

2. drop the column: alter table [table name] drop column [column name]

3. add new column: alter table [table name] add column [column name] [column type]

4. reorg table [table name]

5. maybe need to import original data