DB2 新增主键

DB2 新增主键

1. 非空约束
   A. 删除字段为空的记录
   DELETE FROM [TABLE] WHERE [COLUMN] IS NULL
   B. 设置非空约束
   ALTER TABLE [TABLE] ALTER [COLUMN] SET NOT NULL
2. 主键约束
   A. 删除重复的记录
   SELECT ID FROM (
   SELECT ID, COUNT(ID) AS NUM FROM [COLUMN] WHERE CREATE_TIME > ‘2016-02-01’ GROUP BY ID
   ) A WHERE A.NUM > 1;
   DELETE ~;
   B.设置主键约束
   ALTER TABLE HOST_MESSAGE ADD constraint PK_ID primary key(ID)