create  procedure add_col(
    in model_name text,
    in col_name text,
    in col_info text,
    out result text
)
begin
    if not exists( select * from information_schema.COLUMNS where TABLE_NAME = model_name and COLUMN_NAME = col_name) then
        set @ddl=CONCAT('alter table ', model_name, ' add column ', col_name, col_info);
        prepare stmt from @ddl;
        execute stmt;
        set result = 'success';
    else
        set result = 'exists';
    end if;
end;

set @result = '';
call add_col('dc_employee','senior_1 ','tinyint(1) NULL DEFAULT 0 COMMENT "是否是高级用户，0 不是  1 是"',@result);
select @result;