java 如何从 ResultSet 对象中获取 COUNT？
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How to get COUNT from ResultSet object?
提问by gjw80
I am passing the following query to a ResultSet object:
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";
I want to capture the counts I am getting for each SOURCE and sum them into a total. How can I capture these counts via ResultSet since COUNT isn't a column name in the ResultSet and I don't think I can return it's value via rs.getInt("COUNT")?
我想捕获我为每个 SOURCE 获得的计数并将它们加总。我如何通过 ResultSet 捕获这些计数，因为 COUNT 不是 ResultSet 中的列名，而且我认为我无法通过 返回它的值rs.getInt("COUNT")？
回答by piokuc
getIntis overloaded, use index (an int) instead of a column name:
getInt被过载，使用索引（一个int），而不是列名：
rs.getInt(1); // the first column is 1
回答by Vjy
Try having alias
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";
回答by Raj Bhatta
I Think it is better to use
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();
回答by Kunal Kakkad
I think "getColumnCount" retinto number of column in a table instead of number of rows...
我认为“getColumnCount”retinto 表中的列数而不是行数......
