修改数据表:[]中内容可省略的,tbl_name表名,col_name列名,column_definition 属性 添加单列:ALTER TABLEtbl_name ADD [COLUMN] col_name column_definition [FIRST|AFTER col_name]; 添加多列:ALTER TABLEtbl_name ADD [COLUMN] (col_name column_definition,...); 删除列: ALTER TABLE tbl_name DROP [COLUMN] col_name; 添加主键:ALTER TABLEtbl_name ADD [CONSTRAINT[symbol]] PRIMARY KEY [index_type](index_col_name,...); 删除主键:ALTER TABLEtbl_name DROP PRIMARY KEY; 添加唯一约束:ALTER TABLEtbl_name ADD [CONSTRAINT[symbol]] UNIQUE [INDEX|KEY][index_name][index_type](index_col_name,...) 删除唯一约束:ALTERTABLE tbl_name DROP {INDEX | KEY} index_name; 添加外键约束:ALTERTABLE tbl_name ADD[CONSTRAINT[symbol]]FOREIGN KEY [index_name](index_col_name,...) reference_definition; 删除外键约束:ALTERTABLE tbl_name DROP FOREIGN KEY fk_symbol; 注:fk_symbol为外键约束名称,通过查看数据表信息获得 添加/删除默认约束:ALTERTABLE tbl_name ALTER [COLUMN] col_name {SETDEFAULT literal |DROP DEFAULT }; 修改列定义:ALTERTABLE tbl_name MODIFY [COLUMN] col_name col_definition [FIRST| AFTER col_name]; 修改列属性:ALTERTABLE tbl_name CHANGE [COLUMN] old _col_name new_col_name 数据表改名:ALTERTABLE tbl_name RENAME [TO|AS] new _tbl_name ; RENAMETABLE tbl_name TO new _tbl_name; 注:尽量少修改列名与表名。
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