database – SQLite仅在值不为空时更新列

概述查询：UPDATE item_table SET field1 = field1_spanish,field2 = field2_spanish; 问题：如果field1_spanish不为空,如何仅使用field1_spanish更新field1？如果field2_spanish不为空,我想用field2_spanish更新field2. 谢谢！ http://sqlfiddle.com/#!5 查询：UPDATE item_table SET fIEld1 = fIEld1_spanish,fIEld2 = fIEld2_spanish;

问题：如果fIEld1_spanish不为空,如何仅使用fIEld1_spanish更新fIEld1？如果fIEld2_spanish不为空,我想用fIEld2_spanish更新fIEld2.

谢谢！

解决方法 http://sqlfiddle.com/#!5/58554/1

update  item_tableset  fIEld1 = coalesce(fIEld1_spanish,fIEld1),fIEld2 = coalesce(fIEld2_spanish,fIEld2)

coalesce()函数将返回传递给它的第一个参数,该参数不为null.所以在这种情况下,由于fIEld2_spanish为null,它将fIEld2设置为fIEld2(基本上什么都不做).

要支持空字符串和NulL值,请尝试以下 *** 作：
http://sqlfiddle.com/#!5/b344f/3

update  item_tableset  fIEld1 = case when coalesce(fIEld1_spanish,'') = '' then            fIEld1           else            fIEld1_spanish           end,fIEld2 =  case when coalesce(fIEld2_spanish,'') = '' then            fIEld2           else            fIEld2_spanish           end

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