Postgresql 错误：类型日期的输入语法无效：“日期”&引用；

我有以下psql查询，无法理解为什么会出现错误错误：日期类型的输入语法无效：“”

我的查询如下：

SELECT count(*) FROM campaigns 
WHERE 
    dstart >= '2010-09-02' AND 
    dend <= '2010-09-02' AND 
    status != 'S' AND 
    status != 'C' AND 
    status != 'E' AND 
    (dsignoff <> '' AND dsignoff is not null) AND 
    (dstart <> '' AND dstart is not null) AND 
    (dend <> '' AND dend is not null) AND 
    clientid=20005294;

从活动中选择计数（*）
哪里
dstart>=“2010-09-02”和
dend因为dstart、dend和dsignoff被定义为日期，所以不能将它们与表示无效日期（“”）的字符串进行比较。试试这个：

SELECT count(*) FROM campaigns 
WHERE 
    dstart >= '2010-09-02' AND 
    dend <= '2010-09-02' AND 
    status != 'S' AND 
    status != 'C' AND 
    status != 'E' AND 
    (dsignoff is not null) AND 
    (dstart is not null) AND 
    (dend is not null) AND 
    clientid=20005294;

从活动中选择计数（*）
哪里
dstart>=“2010-09-02”和
丹德