[达梦]达梦数据库的日常操作

一、检查数据库表是否存在

select * from all_Objects where owner ='TEST' and object_type='TABLE' and Object_name like '%HC%';

二、查看建表语句

select DBMS_METADATA.GET_DDL('TABLE','数据库表') from dual;

三、新增字段

alter table "user" add column("is_del" CHAR(1));
comment on column "user" ."is_del" is '删除标志，1是0否';

四、重命名字段名称

alter table "user" rename column "name" to "user_name";

五、修改字段

-- 设置字段默认值
ALTER TABLE "USER" MODIFY  "CREATER_ID" NULL;
-- 修改字段长度
ALTER TABLE "USER" MODIFY  USER_NAME  VARCHAR(150);
-- 修改字段类型(慎用)
alter table "USER" modify  DFQZ int;

六、索引

-- 创建普通索引
CREATE INDEX idx_user_name ON employee(USER_NAME);
SELECT table_name, index_name, index_type
     from user_indexes WHERE index_name='idx_user_name';
-- 删除索引
DROP INDEX idx_user_name;

七、表字段查看

select * from all_tab_columns  where owner='TEST' and Table_Name='USER';
select * from dba_col_comments  where owner='TEST' and Table_Name='USER';