mysql - 尝试从 mysql 存储过程获取 Count 单值

Question

我正在尝试在 mysql 存储过程中进行计数，但无法获得正确的语法 help1

    delimiter//
create procedure get_count_workmen_type(
    IN employee_payroll int,    
    OUT mycount int
)


begin 

SELECT count(*) into mycount from workman
where employee_payroll = employee_payroll

end //
delimiter;

Answer 1

您应该为参数名称添加前缀(我个人使用“p_”)以将它们与列名称等区分开来。例如，whereemployee_payroll=employee_payroll将始终为真，因为它将列与其自身进行比较.

此外，您还应该在 select 语句末尾添加一个分号。

将这两个更改放在一起会得到如下所示的结果:

delimiter //

create procedure get_count_workmen_type(
    IN p_employee_payroll int,    
    OUT p_mycount int
)
begin 
  SELECT count(*) 
  into p_mycount 
  from workman
  where employee_payroll = p_employee_payroll;
end //

delimiter ;