动态传递参数到iReport 4.0.1

Question

我正在使用iReport版本4.0.1。我的问题是

select productcategory as CATEGORYNAME,
    value as VALUE,m_product_id::text,
    product as NAME,count(pricexception) as stock 
from dtawm_stockcalculation_v
where m_product_id=$P{M_Product_ID} or $P{M_Product_ID} is null
    and productcategory=$P{M_Product_Category_ID} 
    or $P{M_Product_Category_ID} is null
group by value,m_product_id,product,productcategory 

我使用两个参数：$P{M_Product_ID}和$P{M_Product_Category_ID}。在这里，我将两个参数的默认值设置为'%'但是我收到错误：

Cannot cast char to string.

Answer 1

通常我们使用“”来设置字符串类型参数的默认值。