#储存过程 中的变量定义
declare 变量名 类型 可选类型 -- 跟建表差不多

create procedure p()
  begin
    declare age int default(18);
    declare number int default 1;
    select age+number;
  end$
/*
mysql> create procedure p()
    ->   begin
    ->     declare age int default(18);
    ->     declare number int default 1;
    ->     select age+number;
    ->   end$
Query OK, 0 rows affected (0.00 sec)

mysql> call p$
+------------+
| age+number |
+------------+
|         19 |
+------------+
1 row in set (0.00 sec)

Query OK, 0 rows affected (0.01 sec)
*/
#储存过程 中， 变量可以运算
#运算结果赋修值给变量用: set age := 运算式
#set age := age + 2

#参数传递

mysql> create procedure p2(number int, age int)
    ->       begin
    ->         select age+number;
    ->       end$
Query OK, 0 rows affected (0.00 sec)

mysql> call p2(1,2)$
+------------+
| age+number |
+------------+
|          3 |
+------------+
1 row in set (0.00 sec)

Query OK, 0 rows affected (0.01 sec)

mysql>