mysql中的IF NULL函数不起作用

Question

我正在进行此查询，但它返回空，我需要返回0，我一直在阅读它，似乎有IFNULL函数，这可以解决，但mysqlWorkbench标记语法错误。

希望有人能帮助我。谢谢

SELECT  IF NULL( "00:00:00", "03:00:00", count(*)
FROM    
        compose.TBL_USERS_TAGS ut  join 
        compose.TBL_USERS u on ut.ID_USER = u.ID_USER  join 
        compose.TBL_TAGS t on ut.ID_TAG = t.ID_TAG  join 
        compose.TBL_IN_OUT i on i.TAG_ADDRESS = t.TAG_ADDRESS  join
        compose.TBL_EVENTS e on e.TAG_ADDRESS  = i.TAG_ADDRESS  

WHERE  (((TIMESTAMPDIFF(SECOND, e.CREATION_DATE,i.IN_DATE)) <='00:02:00' AND 
       (TIMESTAMPDIFF(SECOND, e.CREATION_DATE, i.IN_DATE)) >=  '00:00:00' ))OR
       (e.CREATION_DATE > i.IN_DATE AND e.CREATION_DATE < i.OUT_DATE) AND 
       (TIMESTAMPDIFF(SECOND, i.in_date,i.out_date)) >= '00:00:20' AND 
       (convert(i.IN_DATE, TIME) >= "00:00:00" AND convert(i.OUT_DATE, TIME)  <= "03:00:00")

GROUP BY "00:00:00", "03:00:00",0);

Answer 1

我认为应该是这样的：

SELECT IFNULL（field_name，“value”）;