The process procedure in MySQL

I. Creating process syntax

CREATE PROCEDURE procedure name (parameter list)

Begin

--SQL statement ...

End

-- create a stored procedure delimiter $$ Create procedure my_act () begin    Select *  from goods; End $ $delimiter;

Second, the review process

-- View All Procedures procedure status [ like ' pattern ']; -- View procedure Creation statements Create procedure process name;

Third, Procedure call

-- procedure calls call procedure name ();

Iv. Process Removal

-- Delete procedure Drop procedure process name;

Five, detailed process parameters
Compared to a function, the parameters of the procedure have more than three qualifier modifiers:

1. In-the value is passed, the parameter can be a number or a variable, and the internal modification of the procedure does not affect the external.

2. Out--reference pass, parameter can only be variable. The data in the pre-use variable will be empty. The value generated in the procedure is passed to the external variable at the end of the procedure call.

3. InOut--Reference pass, parameter can only be a variable. External data can be passed to internal use, internal modifications will also be external. The external value is changed only after the call is finished.

How to use: CREATE PROCEDURE procedure name ([in Parameter name parameter type,][out parameter Name argument type,][inout parameter name, parameter type])

--Creating global VariablesSet @ga = 1;Set @gb = 2;Set @gc = 3;--Sample Process Parametersdelimiter $$Create procedurePro_demo (inchXint, Out Yint, InOut Zint)begin    --view changes after the data entry process    Selectx, y, Z; --Modifying the value of a local variable    SetX=  -; SetY=  $; SetZ=  -; --to view the value of a local variable    Selectx, y, Z; --View the value of a global variable to see if the modification of the local variable has an effect on the global    Select @ga,@gb,@gc; --Modifying the value of a global variable    Set @ga = 'a'; Set @gb = 'b'; Set @gc = 'C'; --View the value of the global variable before the call ends to observe the change to the global variable after the procedure call ends    Select @ga,@gb,@gc;End$ $delimiter;--Call ProcedureCall Pro_demo (@ga,@gb,@gc);--observe the value of the global variable again after the procedure call endsSelect @ga,@gb,@gc;

The process procedure in MySQL