修改表里一个字段的类型，怎样写SQL语句？

Question

alter table table_name modify(colname type);SQL> desc tb04;
 名称                                                  空值?    类型
 ----------------------------------------------------- -------- ----------------
 WZBH                                                           VARCHAR2(10)
 KCSL                                                           VARCHAR2(10)
 KCJE                                                           VARCHAR2(10)
SQL>  alter table tb04  modify(wzbh date);表已更改。SQL> desc tb04;
 名称                                                  空值?    类型
 ----------------------------------------------------- -------- ----------------
 WZBH                                                           DATE
 KCSL                                                           VARCHAR2(10)
 KCJE                                                           VARCHAR2(10)SQL>