問題文
A query builds a mailing line by concatenating a street column and a suite column with the concatenation operator. For some rows the suite column holds a null. Those rows still show the street text in the output. Which statement explains that result?
選択肢
- The concatenation operator converts a null operand into a single blank so the street text keeps its own length and one space joins the two parts.
- The concatenation operator raises the row to the next operand so the street text moves up and the suite column is read from the following row.
- The concatenation operator treats a null operand as an empty string so the street text survives and the missing suite part adds nothing to the line.
- The concatenation operator drops a null operand from the row so the row leaves the result set and the street text comes from a second pass.