問題文
A developer combines two queries with UNION. The first query selects three columns and the second selects three columns as well, but the third column is a number in one query and a character value in the other. What does the server require here?
選択肢
- The corresponding expressions have to match in number and they have to sit in the same data type group.
- The corresponding expressions have to be listed in the same order and the types are widened.
- The corresponding expressions have to carry the same column name and the types are checked later.
- The corresponding expressions have to match in number and the server converts the number into a character value on its own.