Postgres中的ALTER表查询

Question

我试图将表中一列的数据类型从biginteger更改为varchar。

myproject-# \d+ product_awbstock
                         Table "public.product_awbstock"
      Column       |           Type           | Modifiers | Storage | Description 
-------------------+--------------------------+-----------+---------+-------------
 airwaybill_number | bigint                   | not null  | plain   | 
 used              | boolean                  | not null  | plain   | 
 created           | timestamp with time zone | not null  | plain   | 
 modified          | timestamp with time zone | not null  | plain   | 
Indexes:
    "product_awbstock_pkey" PRIMARY KEY, btree (airwaybill_number)
    "product_awbstock_used" btree (used)

我正在使用此查询，也给出了错误。

alter table product_awbstock ALTER  COLUMN airwaybill_number TYPE varchar(15);

错误：外键约束“ awbstock_id_refs_airwaybill_number_d438187b”无法实现

详细信息：关键列“ awbstock_id”和“ airwaybill_number”具有不兼容的类型：bigint和字符变化。

Answer 1

你应该：

1. 将主键约束放在第一个表上

ALTER TABLE product_awbstock DROP CONSTRAINT product_awbstock_pkey;

2. 在第二个表上删除外键约束

ALTER TABLE ??? DROP CONSTRAINT awbstock_id_refs_airwaybill_number_d438187b;

3. 更改两个表上的列数据类型

ALTER TABLE product_awbstock ALTER COLUMN airwaybill_number TYPE varchar(15);

ALTER TABLE ??? ALTER COLUMN airwaybill_id TYPE varchar(15);

4. 重新创建以前删除的约束

ALTER TABLE product_awbstock ADD CONSTRAINT product_awbstock_pkey PRIMARY KEY (airwaybill_number);

ALTER TABLE ??? ADD CONSTRAINT awbstock_id_refs_airwaybill_number_d438187b FOREIGN KEY (awbstock_id) REFERENCES product_awbstock (airwaybill_number);