Several mysql statements commonly used in PHP_PHP tutorial

Show database or table:
show databases;//Then you can use database_name;
show tables;
Change table name:
alter table table_name rename new_t;
Add columns:
alter table table_name add column c_n column attributes;
Delete column:
alter table table_name drop column c_n;
Create index:
alter table c_table add index (c_n1,c_n2);
alter table c_table add unique index_name(c_n);
alter table c_table add primary key(sid);
Delete index:
alter table c_table drop index c_n1;
Change column information:
alter table t_table change c_1 c_1 varchar(200);
alter table t_table modify 1 c_1 varchar(200);
insert statement:
insert into table_name (c_1,c_2)
values ​​(x1,1 );
update statement:
update table_name set c_1 =1 where c_2=3;
Delete database or table:
drop table table_name;
drop database database_name;//Use mysql_drop_db() Can be deleted.