MySQL | 修改数据表结构

数据定义语言：字段约束

添加字段

	ALTER TABLE student
	ADD address VARCHAR(200) NOT NULL,
	ADD home_tel char(11) NOT NULL;

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修改字段类型和约束

	ALTER TABLE student
	MODIFY home_tel VARCHAR(20) NOT NULL;
	DESC student;

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修改字段名称

	DESC student;
	ALTER TABLE student
	CHANGE address home_address VARCHAR(200) NOT NULL;

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删除字段

	DESC student;
	ALTER TABLE student
	DROP home_address,
	DROP home_tel;

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总结语句

	ALTER TABLE student # DDL 语句 没有操作数据类型
	ADD address VARCHAR(200) NOT NULL,
	ADD home_tel char(11) NOT NULL;
	ALTER TABLE student # DDL 语句 没有操作数据类型
	MODIFY home_tel VARCHAR(20) NOT NULL;
	DESC student;
	ALTER TABLE student # DDL 语句 没有操作数据类型
	CHANGE address home_address VARCHAR(200) NOT NULL;
	ALTER TABLE student # DDL 语句 没有操作数据类型
	DROP home_address,
	DROP home_tel;

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