我有一个名为“test”的数据库,其中我有一个名为“first”的表,其中包含原始数据,我想获取此表数据。为了从“第一”表中获取数据,我必须使用什么样的准备语句?以下是我正在尝试的代码。任何帮助或指导都会很明显。
@Path("/database") // Specific URL
@GE
@Produces(MediaType.TEXT_PLAIN)
public String returnDB_Status() throws Exception {
PreparedStatement query = null;
String result = null;
Connection conn = null;
try {
conn = mysql_prac.dbConn().getConnection(); // this works fine ...
query = conn.prepareStatement("SELECT * from first" ); // Table named as "first" is placed inside the connected database.
ResultSet rs = query.executeQuery();
result = "Data received : " + rs;
query.close();
} catch (Exception e) {
e.printStackTrace();
} finally {
if (conn != null)
conn.close();
}
return result;
}
和使用的源代码获得连接
public class mysql_prac {
private static DataSource mysql_prac = null;
private static Context context = null;
public static DataSource dbConn() throws Exception {
if (mysql_prac != null) {
return mysql_prac;
}
try {
if (context == null) {
context = new InitialContext();
}
mysql_prac = (DataSource) context.lookup("JDBC_ref"); //JNDI ID (JDBC_REF)
} catch (Exception e) {
e.printStackTrace();
}
return mysql_prac;
}
}
答案 0 :(得分:0)
您必须遍历ResultSet
以获取每行的字段。所以我做了以下编辑和一些评论。请注意评论。
try {
conn = mysql_prac.dbConn().getConnection(); // this works fine ...
query = conn.prepareStatement("SELECT * from first" ); // Table named as "first" is placed inside the connected database.
ResultSet rs = query.executeQuery();//You must loop through the results set to get the fields of each row
while(rs.next()){
String dbUserID = rs.getString("column1");//this is just an example to retrieve all data in the column called 'column1'
result = "Data received : " + dbUserID;
System.out.println(result);
}
query.close();
} catch (Exception e) {
e.printStackTrace();
} finally {
if (conn != null)
conn.close();
}