摘要：
本文将深入探讨SQL Server数据库中ALTER MESSAGE TYPE语法的使用，包括其基本概念、语法结构、使用场景以及在实际操作中的注意事项。通过详细的代码示例和解释，帮助读者更好地理解和应用ALTER MESSAGE TYPE语法，以实现消息类型的修改和管理。
一、
在SQL Server数据库中，消息类型是用于定义消息的格式和内容的结构。ALTER MESSAGE TYPE语法允许用户修改现有的消息类型，包括更改消息的名称、数据类型、长度等属性。本文将围绕这一主题，详细介绍ALTER MESSAGE TYPE语法的使用。
二、基本概念
1. 消息类型（Message Type）
消息类型是SQL Server中用于定义消息格式和内容的结构。它类似于其他数据库中的数据类型，但专门用于服务 broker。
2. ALTER MESSAGE TYPE
ALTER MESSAGE TYPE语法用于修改现有的消息类型。通过使用此语法，可以更改消息的名称、数据类型、长度等属性。
三、语法结构
ALTER MESSAGE TYPE [schema_name.]message_type_name
[WITH SCHEMABINDING]
[MODIFY NAME = new_name]
[MODIFY VALUE = new_value]
[MODIFY DATA TYPE = data_type]
[MODIFY LENGTH = length]
[MODIFY MAX_LENGTH = max_length]
[MODIFY ENCODING = encoding]
[MODIFY SCHEMA = schema_name]
[MODIFY VALUE ON NULL = value_on_null]
[MODIFY DEFAULT = default_value]
[MODIFY NULL ON DEFAULT = null_on_default]
[MODIFY NULL ON NULL = null_on_null]
[MODIFY NULL ON NOT NULL = null_on_not_null]
[MODIFY NULL ON UNIQUE = null_on_unique]
[MODIFY NULL ON PRIMARY KEY = null_on_primary_key]
[MODIFY NULL ON FOREIGN KEY = null_on_foreign_key]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY KEY CONSTRAINT = null_on_primary_key_constraint]
[MODIFY NULL ON CHECK CONSTRAINT = null_on_check_constraint]
[MODIFY NULL ON DEFAULT CONSTRAINT = null_on_default_constraint]
[MODIFY NULL ON FOREIGN KEY CONSTRAINT = null_on_foreign_key_constraint]
[MODIFY NULL ON UNIQUE CONSTRAINT = null_on_unique_constraint]
[MODIFY NULL ON PRIMARY
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