Plsql parameters IN and OUT

     scott.pro_para_inout(p_dname  out scott.dept.dname                                            p_loc out scott.dept.locTYPE)     dbms_output.put_line(p_dname     dbms_output.put_line(p_loc    pro_para_inout;

Call

  ;

 

Result

When the parameter type is OUT, the value in the original record (v_dept) does not exist. If it is in out, the original record value remains the same.

Of course, you can set it when you use it according to the actual situation. However, if you want to reset the value under certain circumstances, you can do nothing without meeting the conditions. If the original value remains unchanged, it is wrong to write it as OUT.

This is the official explanation of oracle parameter value transfer or reference transfer.

Summary of Subprogram Parameter Modes

Table 8-1 summarizes the characteristics of parameter modes.

Table 8-1 Parameter Modes

IN	OUT	IN OUT
The default	Must be specified	Must be specified
Passes a value to the subprogram	Returns a value to the caller	Passes an initial value to the subprogram and returns an updated value to the caller
Formal parameter acts like a constant	Formal parameter acts like an uninitialized variable	Formal parameter acts like an initialized variable
Formal parameter cannot be assigned a value	Formal parameter must be assigned a value	Formal parameter shocould be assigned a value
Actual parameter can be a constant, initialized variable, literal, or expression	Actual parameter must be a variable	Actual parameter must be a variable
Actual parameter is passed by reference (the caller passes the subprogram a pointer to the value)	Actual parameter is passed by value (the subprogram passes the caller a copy of the value) unlessNOCOPYIs specified	Actual parameter is passed by value (the caller passes the subprogram a copy of the value and the subprogram passes the caller a copy of the value) unlessNOCOPYIs specified