[ http://issues.apache.org/jira/browse/DERBY-1515?page=comments#action_12447952 ] Bryan Pendleton commented on DERBY-1515: ----------------------------------------
Knut Anders pointed out that it isn't necessary to rename column c1 to c1_oldtype. The technique can be simplified to: 1) ALTER TABLE t ADD COLUMN c1_newtype NEWTYPE; 2) UPDATE t SET c1_newtype = c1; 3) ALTER TABLE t DROP COLUMN c1; 4) ALTER TABLE t RENAME COLUMN c1_newtype to c1; > Provide ALTER TABLE functionality to change a column's data type > ---------------------------------------------------------------- > > Key: DERBY-1515 > URL: http://issues.apache.org/jira/browse/DERBY-1515 > Project: Derby > Issue Type: New Feature > Components: Documentation, SQL > Affects Versions: 10.1.1.0, 10.2.1.6, 10.1.2.1, 10.1.3.1 > Reporter: Bryan Pendleton > Priority: Minor > > Derby should provide a feature which allows a user to change the data type of > an existing column in an existing table. > Currently, there exists the statement: > ALTER TABLE tablename ALTER COLUMN columnname SET DATA TYPE datatype > However, this statement currently only allows increasing the length of a > VARCHAR column. You are not allowed to decrease the width or to change the > data type. > It would be nice if this restriction could be lifted, and the datatype could > be changed. -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://issues.apache.org/jira/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira
