ALTER TABLE [dbo].[表名] ADD CONSTRAINT [DF_表名_列名] DEFAULT ((默认值)) FOR [列名]
ALTER TABLE QA_API ADD CONSTRAINT [DF_QA_API_deletedflag] DEFAULT (0) FOR API_DELETED_FLAG
ALTER TABLE [dbo].[表名] ADD CONSTRAINT [DF_表名_列名] DEFAULT ((默认值)) FOR [列名]
ALTER TABLE QA_API ADD CONSTRAINT [DF_QA_API_deletedflag] DEFAULT (0) FOR API_DELETED_FLAG