mysql怎么修改字符集？

ALTER TABLE  表名 DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;

SELECT TABLE_NAME,CONCAT('ALTER TABLE  ',TABLE_NAME,' DEFAULT CHARACTER SET ',a.DEFAULT_CHARACTER_SET_NAME,' COLLATE ',a.DEFAULT_COLLATION_NAME,';') executeSQL FROM information_schema.SCHEMATA a,information_schema.TABLES bWHERE a.SCHEMA_NAME=b.TABLE_SCHEMAAND a.DEFAULT_COLLATION_NAME!=b.TABLE_COLLATIONAND b.TABLE_SCHEMA='数据库名'

ALTER TABLE  表名 CHANGE  列名  列名  VARCHAR( 100 ) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL;

select b.table_name,b.column_name,b.character_set_name,b.collation_name

,CONCAT('ALTER TABLE ',b.table_name,' MODIFY ',b.column_name,' ',b.DATA_TYPE,'(',b.CHARACTER_MAXIMUM_LENGTH,') ',CASE WHEN b.COLUMN_DEFAULT IS NULL THEN ''  ELSE CONCAT('DEFAULT \'',b.COLUMN_DEFAULT,'\'') END,' COMMENT \'',b.COLUMN_COMMENT,'\';') executeSQL from information_schema.TABLES a,information_schema.COLUMNS b where  b.character_set_name IS NOT NULL and a.TABLE_SCHEMA=b.TABLE_SCHEMA AND a.TABLE_NAME=b.TABLE_NAMEAND a.TABLE_COLLATION!=b.COLLATION_NAMEand a.TABLE_SCHEMA='数据库名'