尝试在PostgreSQL中修改约束
我检查了Oracle提供的文档找到了一种修改约束的方法，而无需删除表格。问题是修改时出错，因为无法识别关键字。使用PostgreSQL的EMS SQL Manager。
Alter table public.public_insurer_credit MODIFY CONSTRAINT public_insurer_credit_fk1 deferrable,initially deferred;我可以用以下方法删除约束来解决这个问题：
ALTER TABLE "public"."public_insurer_credit"DROP CONSTRAINT "public_insurer_credit_fk1" RESTRICT;ALTER TABLE "public"."public_insurer_credit"ADD CONSTRAINT "public_insurer_credit_fk1" FOREIGN KEY ("branch_id","order_id","public_insurer_id") REFERENCES "public"."order_public_insurer"("branch_id","order_id","public_insurer_id") ON UPDATE CASCADE ON DELETE NO ACTION DEFERRABLE INITIALLY DEFERRED;
解决方案:
根据正确的手册(由PostgreSQL提供，而不 由Oracle提供），ALTER TABLE句子中没有可用的修改约束：
这是正确手册的链接:
http://www.postgresql.org/docs/current/static/sql-
altertable.html
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