ALTER DATABASE db_name DEFAULT CHARACTER SET character_name [COLLATE …];

ALTER TABLE tbl_name DEFAULT CHARACTER SET character_name [COLLATE…];

ALTER TABLE tbl_name CHANGE c_name c_name CHARACTER SET character_name [COLLATE …];

ALTER TABLE logtest CHANGE title title VARCHAR(100) CHARACTER SET utf8 COLLATE utf8_general_ci;

ALTER TABLE myAPP_cont1 CHANGE titles titles VARCHAR(100) CHARACTER SET utf8;

SHOW CREATE DATABASE db_name;

SHOW CREATE TABLE tbl_name;

SHOW FULL COLUMNS FROM tbl_name;

ALTER TABLE 表名 ADD PRIMARY KEY (字段名);

alter table table_a ADD PRIMARY KEY (id);

ALTER TABLE 表名 DROP PRIMARY KEY;

alter table table_a DROP PRIMARY KEY;

ALTER TABLE 表名 ADD UNIQUE 索引名(字段名);

alter table table_a ADD UNIQUE column_a_unique_index (column_a);

ALTER TABLE 表名 ADD INDEX 索引名 (字段名);

alter table table_a ADD INDEX column_a_index (column_a);

ALTER TABLE 表名 DROP INDEX 索引名;

alter table table_a DROP INDEX column_a_index;