当我从命令行调用存储过程时,我得到以下内容。
CALL `events`.`get_event_by_id`(10)
+---------+----------+-------------+---------------------+---------------------+---------------------+--------+----------+
| evet_id | name | description | starttime | endtime | last_modified | active | addre_id |
+---------+----------+-------------+---------------------+---------------------+---------------------+--------+----------+
| 10 | samole 3 | sanely | 2013-11-27 17:37:00 | 2013-11-27 18:09:00 | 2013-11-27 09:37:42 | 1 | 20 |
+---------+----------+-------------+---------------------+---------------------+---------------------+--------+----------+
1 row in set (0.00 sec)
+---------+------------+---------+
| user_id | username | picture |
+---------+------------+---------+
| 1 | jamess2000 | NULL |
| 2 | yferna2012 | NULL |
+---------+------------+---------+
2 rows in set (0.00 sec)
+----------+------------------------------+---------------------+-------------+--------+
| addre_id | street | name | description | active |
+----------+------------------------------+---------------------+-------------+--------+
| 20 | Schieffelin | Manhattan Ville Loc | NULL | 1 |
+----------+------------------------------+---------------------+-------------+--------+
以下是我的Java代码片段
String SP_GET_EVENT_BY_ID = "CALL `events`.`get_event_by_id`(?)";
String PROC_PARAM_EVENT_ID = "evet_id";
mCallableStatement = mConnection.prepareCall(SP_GET_EVENT_BY_ID);
mCallableStatement.setInt(10, PROC_PARAM_EVENT_ID);
执行语句时,只返回event_table结果。 我用以下内容阅读了查询:
ResultSet reader = mCallableStatement.executeQuery();
while(reader.next())
{
//etc..... here i assign db values to properties.
}
我试图避免向数据库发出多个请求,因为它非常慢(300毫秒,具体取决于多少结果)
甚至可能吗?
答案 0 :(得分:6)
我找到了这篇很棒的文章。 http://www.herongyang.com/JDBC/MySQL-CallableStatement-Multiple-ResulSet.html
以下是该文章的代码。
/**
* MySqlCallMultipleResultSet.java
* Copyright (c) 2007 by Dr. Herong Yang. All rights reserved.
*/
import java.sql.*;
public class MySqlCallMultipleResultSet {
public static void main(String [] args) {
Connection con = null;
try {
com.mysql.jdbc.jdbc2.optional.MysqlDataSource ds
= new com.mysql.jdbc.jdbc2.optional.MysqlDataSource();
ds.setServerName("localhost");
ds.setPortNumber(3306);
ds.setDatabaseName("HerongDB");
ds.setUser("Herong");
ds.setPassword("TopSecret");
con = ds.getConnection();
// Create CallableStatement
CallableStatement cs = con.prepareCall("CALL HeadTail(?)");
// Register OUT parameters
cs.registerOutParameter(1, java.sql.Types.INTEGER);
// Execute the CALL statement and expecting multiple result sets
boolean isResultSet = cs.execute();
// First ReulstSet object
if (!isResultSet) {
System.out.println("The first result is not a ResultSet.");
return;
}
// First ReulstSet object
System.out.println("Head of the table:");
ResultSet res = cs.getResultSet();
while (res.next()) {
System.out.println(" "+res.getInt("ID")
+", "+res.getString("FirstName")
+", "+res.getString("LastName")
+", "+res.getTimestamp("ModTime"));
}
res.close();
// Move to the next result
isResultSet = cs.getMoreResults();
if (!isResultSet) {
System.out.println("The next result is not a ResultSet.");
return;
}
// Second ReulstSet object
System.out.println("Tail of the table:");
res = cs.getResultSet();
while (res.next()) {
System.out.println(" "+res.getInt("ID")
+", "+res.getString("FirstName")
+", "+res.getString("LastName")
+", "+res.getTimestamp("ModTime"));
}
res.close();
// Retrieve OUT parameters
System.out.println("Total number of records: "+cs.getInt(1));
// Close resource
cs.close();
con.close();
} catch (Exception e) {
System.err.println("Exception: "+e.getMessage());
e.printStackTrace();
}
}
}
答案 1 :(得分:1)
public static void executeProcedure(Connection con) {
try {
CallableStatement stmt = con.prepareCall(...);
..... //Set call parameters, if you have IN,OUT, or IN/OUT parameters
boolean results = stmt.execute();
int rsCount = 0;
// Loop through the available result sets.
while (results) {
ResultSet rs = stmt.getResultSet();
// Retrieve data from the result set.
while (rs.next()) {
// using rs.getxxx() method to retrieve data
}
rs.close();
// Check for next result set
results = stmt.getMoreResults();
}
stmt.close();
}
catch (Exception e) {
e.printStackTrace();
}
}
答案 2 :(得分:0)
根据Statement.getMoreResults()的Javadocs,您还应该在查找更多结果集时检查getUpdateCount() != -1
。
此代码适用于Sybase以及除Oracle以外的许多其他数据库:
Connection conn = null;
try {
Class.forName("com.sybase.jdbc3.jdbc.SybDriver");
conn = DriverManager.getConnection(url, username, password);
CallableStatement call = conn.prepareCall("{call events.get_event_by_id(?)}");
call.setInt("@evet_id", 10);
boolean moreResults = call.execute();
int updateCount = call.getUpdateCount();
while (moreResults || updateCount != -1) {
if (moreResults) {
ResultSet rs = call.getResultSet();
processResults(rs);
}
moreResults = call.getMoreResults();
updateCount = call.getUpdateCount();
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
conn.close();
} catch (Exception e) {}
}
https://docs.oracle.com/javase/7/docs/api/java/sql/Statement.html#getMoreResults()