发表日期: 2022-11-30 15:19:08 浏览次数:334
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币安推出的交易所平台币模式首次让用户参与到平台建设当中,享受平台发展的红利。据悉,币安将平台当季净利润的20%用于BNB回购,通过市场交易行为兑现平台的预期价值,以维持平台币价稳步上涨。这一做法类似于证券市场中以现金流作抵押发行债券,后期再通过利润等方式回购的模式。
随后,火币、OKCoin等各大平台也纷纷推出平台币,在BNB的基础上增加了更多权益,交易所的竞争逐渐演变为平台币、甚至平台生态的竞争。
ALTER FOREIGN TABLE — 更改一个外部表的定义
ALTER FOREIGN TABLE [ IF EXISTS ] [ ONLY ] name [ * ] action [, ... ] ALTER FOREIGN TABLE [ IF EXISTS ] [ ONLY ] name [ * ] RENAME [ COLUMN ] column_name TO new_column_nameALTER FOREIGN TABLE [ IF EXISTS ] name RENAME TO new_nameALTER FOREIGN TABLE [ IF EXISTS ] name SET SCHEMA new_schema其中 action 是以下之一: ADD [ COLUMN ] column_name data_type [ COLLATE collation ] [ column_constraint [ ... ] ] DROP [ COLUMN ] [ IF EXISTS ] column_name [ RESTRICT | CASCADE ] ALTER [ COLUMN ] column_name [ SET DATA ] TYPE data_type [ COLLATE collation ] ALTER [ COLUMN ] column_name SET DEFAULT expression ALTER [ COLUMN ] column_name DROP DEFAULT ALTER [ COLUMN ] column_name { SET | DROP } NOT NULL ALTER [ COLUMN ] column_name SET STATISTICS integer ALTER [ COLUMN ] column_name SET ( attribute_option = value [, ... ] ) ALTER [ COLUMN ] column_name RESET ( attribute_option [, ... ] ) ALTER [ COLUMN ] column_name SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN } ALTER [ COLUMN ] column_name OPTIONS ( [ ADD | SET | DROP ] option ['value'] [, ... ]) ADD table_constraint [ NOT VALID ] VALIDATE CONSTRAINT constraint_name DROP CONSTRAINT [ IF EXISTS ] constraint_name [ RESTRICT | CASCADE ] DISABLE TRIGGER [ trigger_name | ALL | USER ] ENABLE TRIGGER [ trigger_name | ALL | USER ] ENABLE REPLICA TRIGGER trigger_name ENABLE ALWAYS TRIGGER trigger_name SET WITH OIDS SET WITHOUT OIDS INHERIT parent_table NO INHERIT parent_table OWNER TO { new_owner | CURRENT_USER | SESSION_USER } OPTIONS ( [ ADD | SET | DROP ] option ['value'] [, ... ])
ALTER FOREIGN TABLE
更改一个现有外部表的定义。 有几种子形式:
ADD COLUMN
这种形式使用与CREATE FOREIGN TABLE相同的语法把 一个新的列增加到该外部表。和为常规表增加一列不同,这种形式并不影响底层 的存储:这个动作只是简单地声明通过该外部表可以访问某个新的列而已。
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