sql - DB2(v10.5.0.5) 如何将自增列添加到已存在的表中

Question

我正在尝试在 DB2 的现有表中添加一个自动递增列。

DB2 版本是 v10.5.0.5。

以下是我的查询:

alter table DB2INST1.AAA_BJ_BOND 
ADD COLUMN id INTEGER NOT NULL DEFAULT 0;

ALTER TABLE DB2INST1.AAA_BJ_BOND ALTER COLUMN id 
set generated always as identity (start with 1);

但是我得到了以下错误:

"com.ibm.db2.jcc.am.SqlSyntaxErrorException: ALTER TABLE "DB2INST1.AAA_BJ_BOND" 
specified attributes for column "ID" that are not compatible with the existing 
column.. SQLCODE=-190, SQLSTATE=42837, DRIVER=4.13.127"

我该怎么做才能解决这个问题？

Answer 1

您必须先删除列的默认值。 SQL0190N的描述中提到了这一点:

If SET GENERATED ALWAYS AS (expression) is specified, but the column is already defined with a form of generation (default, identity, or expression) and there is no corresponding DROP in the same statement.

ALTER TABLE DB2INST1.AAA_BJ_BOND 
ALTER COLUMN id drop default;

ALTER TABLE DB2INST1.AAA_BJ_BOND ALTER COLUMN id 
set generated always as identity (start with 1);