Question

我将以下查询传递给ResultSet对象：

String query = "SELECT COUNT( DISTINCT KEY ), SOURCE FROM MY_TBL\n" +
            "GROUP BY SOURCE\n" +
            "ORDER BY SOURCE";

我希望捕获每个SOURCE获得的计数并将它们总计为总计。如何通过ResultSet捕获这些计数，因为COUNT不是ResultSet中的列名，我认为我不能通过rs.getInt("COUNT")返回它的值？

Answer 1

getInt为overloaded，使用索引（int）代替列名：

 rs.getInt(1); // the first column is 1

Answer 2

尝试使用别名

String query = "SELECT COUNT( DISTINCT KEY ) AS COUNT, SOURCE FROM MY_TBL\n" +
        "GROUP BY SOURCE\n" +
        "ORDER BY SOURCE";

Answer 3

我认为最好使用

Statement st = conn.createStatement();
ResultSet rs = st.executeQuery("SELECT * from Customer");
ResultSetMetaData rsmd = rs.getMetaData();

int numCols = rsmd.getColumnCount();

Answer 4

我认为＆＃34; getColumnCount＆＃34; retinto表中的列数而不是行数...

如何从ResultSet对象获取COUNT？

4 个答案: