通常在POSTGRES中删除外键

Question

我怎么能放弃Foreign keys一般.我的意思是,如果我在表中有很多外键约束.喜欢

MonthlyEvaluatedBudgetTable Contraints:

• budgetid_pk(主键)
• branchid_fk(外键)
• accountid_fk(外键)
• dept_fk(外键)

在postgres中是否有一种方法可以放弃所有外键,而不是特定地放在现有表中？我使用这行代码删除现有表中的外键.

    ALTER TABLE "public"."monthlyevaluatedbudgettable"
    DROP CONSTRAINT "accountid_fk";

但我想放弃它没有专门输入查询accountid_fk,branchid_fk,dept_fk.有没有办法呢？提前致谢.

Answer 1

将其循环到DO语句中,如:

b=# create table a (a int primary key, b int unique);
CREATE TABLE
b=# create table b (a int references a(a), b int references a(b));
CREATE TABLE
b=# do
$$
declare r record;
begin
for r in (select constraint_name from information_schema.table_constraints where table_schema = 'public' and table_name='b') loop
  raise info '%','dropping '||r.constraint_name;
  execute CONCAT('ALTER TABLE "public"."b" DROP CONSTRAINT '||r.constraint_name);
end loop;
end;
$$
;
INFO:  dropping b_a_fkey
INFO:  dropping b_b_fkey
DO

Answer 2

感谢Vao Tsun的解决方案。它帮助了我。

在我的情况下（Posgresql 9.6）我只需要添加一个小的“改进”

and constraint_name like 'fk_%' 防止错误的附加约束，例如：

PG::SyntaxError：错误：“2200”处或附近的语法错误第 1 行：ALTER TABLE“关系”DROP CONSTRAINT 2200_856906_1_no...

execute <<-SQL.squish
  DO $$
  declare r record;
  begin
    for r in (
      select constraint_name
      from information_schema.table_constraints
      where table_name='relationships'
      and constraint_name like 'fk_%'
    ) loop
    raise info '%','dropping '||r.constraint_name;
    execute CONCAT('ALTER TABLE "relationships" DROP CONSTRAINT '||r.constraint_name);
    end loop;
  end;
  $$
SQL