语法：
1.存储过程：
create PROCEDURE name(argment_list)
begin
sql_statement;
end
2.触发器：
create trigger name (before|after) (insert | update | delete) on table_name
for each row
begin
sql_statement;
end
3.游标:
declare cursor_name cursor for select statement;
4.其他语法
declare var_name int; 声明变量
setvar_name = 5; 赋值
-- 或者
set @var_name = 5
例子：
CREATE PROCEDURE `procedure_name`()
BEGIN
Declare found boolean default true;
Declare name varchar(20);
Declare names_cursor cursor for SELECT name FROM user;
DECLARE CONTINUE HANDLER FOR NOT FOUND set found=false;
open names_cursor;
name_loop:LOOP fetch names_cursor into name;
if found then
sql_statement;
else
leave name_loop;
end if;
end LOOP name_loop;
close names_cursor;
END
create trigger trigger_name before insert on user
for each row
begin
set @userid = NEW.userid;
set @name = NEW.name;
set @count= (select count(userid) from user where userid=@userid and name = @name);
if @count=1 then
-- this user already exists,throw exception
insert into Error_message_ChannelIdToClientMustBeUnique values(1);
end if;
end
