有关union和union all，以下说法正确的是（）
According to labor law, which of the following management actions are prohibited during a union organizing drive?A . Forbidding employees from distributing union literature in working areasB . Implementing previously scheduled pay raisesC . Forbidding unions from soliciting workers during working hoursD . Circulating anti-union petitionsE . All of the above
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162 According to labor law, which of the following management actions are prohibited during a union organizing drive?A. Forbidding employees from distributing union literature in working areasB. Implementing previously scheduled pay raisesC. Forbidding unions from soliciting workers during working hoursD. Circulating anti-union petitionsE. All of the above
若有以下说明和定义语句，则变量w在内存中所占的字节数是 【19】 。union aa {float x; float y; char c［6］; };struct st{ union aa v; float w［5］; double ave; } w;
UNION中ALL关键字的作用是在结果集中所有行全部列出，不管是否有重复行。 ()
下面对 union 的描述正确的是( )A.union 只连接结果集完全一样的查询语句B.union 可以连接结果集中数据类型个数相同的多个结果集C.union 是筛选关键词，对结果集再进行操作D.任何查询语句都可以用 union 来连接
URL的全称是( )。A.Union Resource LocalB.Universal Resource LocatorC.Union Reform LocalD.Universal Resource Local
union和union all有什么不同?
