下面是一个示例脚本,用于修改table_name表中所有字段的长度为new_length: SET@table_name='table_name';SET@new_length=new_length;SELECTCOLUMN_NAMEFROMinformation_schema.COLUMNSWHERETABLE_NAME=@table_name;SET@sql=NULL;SELECTGROUP_CONCAT(CONCAT('MODIFY COLUMN ',COLUMN_NAME,' VARCHAR(',@new_length,')...
cursor = conn.cursor() cursor.execute(f"SELECT column_name, data_type FROM information_schema.columns WHERE table_schema = '{database}' AND table_name = '{table_name}' AND data_type = '{data_type}'") fields = cursor.fetchall() cursor.close() conn.close() return fields def generate...
i can alter single columns by using modify statement But how to alter multiple columns Subject Written By Posted how to alter multiple columns siva shanmugam November 07, 2008 12:36AM Re: how to alter multiple columns Rick James November 07, 2008 11:27PM ...
方法2:创建表后,添加字段的注释信息 ALTERTABLEemployee CHANGECOLUMNemployee_name employee_namevarchar(30)DEFAULTNULLCOMMENT'员工姓名2';ALTERTABLEemployee MODIFYCOLUMNemployee_namevarchar(30)DEFAULTNULLCOMMENT'修改后的字段注释'; 不过有点奇怪的是,MySQL数据库修改字段的注释或给字段添加注释,都必须加上字段类型,...
#3) MySQL Insert Multiple Rows Next, we will go through the scenario where we have to insert multiple rows into the table with the same INSERT statement. For Example,in this case, we need to mention the column names only once, but we can keep repeating the values for those columns as ...
Multiple-table syntax: DELETE [LOW_PRIORITY] [QUICK] [IGNORE] tbl_name[.*] [, tbl_name[.*]] ... FROM table_references [WHERE where_condition] Or: DELETE [LOW_PRIORITY] [QUICK] [IGNORE] FROM tbl_name[.*] [, tbl_name[.*]] ... ...
If all columns that make up an index are dropped, the index is dropped as well. If you use CHANGE or MODIFY to shorten a column for which an index exists on the column, and the resulting column length is less than the index length, MySQL shortens the index automatically. ...
MODIFY: Can change a column definition but not its name. More convenient than CHANGE to change a column definition without renaming it. With FIRST or AFTER, can reorder columns. ALTER: Used only to change a column default value. CHANGE...
-- 语法 alter table 表名 modify column 字段名 类型;ALTERTABLEtable_nameMODIFYCOLUMNcolumn_name new_data_type[NOTNULL|NULL][DEFAULTnew_default_value];-- 示例:altertabletableNamemodifycolumncitychar(30); 删除列: ALTERTABLEtable_nameDROPCOLUMNcolumn_name;-- 示例:(注:谨慎修改类型,可能会导致原有数...
alter table tbl modify column ID bigint(20) NOT NULL; alter table tbl DROP PRIMARY KEY; alter table tbl add column rowid int(11) NOT NULL AUTO_INCREMENT primary key; alter table tbl ENGINE=InnoDB DEFAULT CHARSET=latin1 COLLATE=latin1_bin; ...