Parameters of the stored procedure

Stored procedure arguments: in parentheses in the stored procedure, you can declare parameters. The syntax is:CREATE PROCEDURE P ([in/out/inout] parameter Name argument type ...) , the MySQL stored procedure parameter will default to in if not explicitly specified in, out, InOut

In: parameters for incoming function

Create procedureP7 (inchNint)begin    DeclareNumint default 0; DeclareTotalint default 0;  whileNum<=N doSetTotal:=Total+num; SetNum:=Num+ 1; End  while; SelectTotal ;End$

Invoke: Call-------->5050 (1+2+3+....+100)/call (+)--------------->55 (1+2+3+.........+10)

Out: An external variable that can be understood as a function to be changed, regardless of what value the variable is outside, the initial value inside is null, and the internal effect on it will change the value of the external variable, that is, the value of the function calculation is mapped to the outside of the function

Create procedureP8 (inchNint, out Totalint)begin    DeclareNumint default 0; SetTotal:= 0;  whileNum<=N doSetTotal:=Total+num; SetNum:=Num+ 1; End  while;End$

Invoke: Call P8 (10,@C); Select @c;-----------------> Printing 55

InOut: declares global for a function internally and may modify the value of the variable

Create procedure int begin    set Age:=+; End$

Call: Set @age: = 20;    Call P9 (@age);     Select @age; Printing 40

Parameters of the stored procedure