java 如何在java中比较两个结果集的值
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/15184100/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
How to compare the values of two resultset in java
提问by
I have two tables. And these tables have the same schema consisting of userid, username. I want to check is there any common usernamein table1and table2.
我有两张桌子。这些表具有相同的架构，由用户 ID、用户名组成。我想看看是否有任何共同username的table1和table2。
rs1 = statement.executeQuery("select username from table1")
rs2 = statement.executeQuery("select username from table2")
My logic is:
我的逻辑是：
while(rs1.next())- compare the value of
rs1with every value ofrs2. Ifthere match found print one of the valueelseprint both the values.
while(rs1.next())- 将 的值
rs1与 的每个值进行比较rs2。 If有匹配找到打印值之一else打印两个值。
Is there a way to achieve this in java... Please anyone help me ... Thanks...
有没有办法在java中实现这一点......请任何人帮助我......谢谢......
采纳答案by NPE
I would use a single SQL statement:
我将使用单个 SQL 语句：
select table1.username from table1, table2 where table1.username = table2.username
This will only return usernames that appear in both tables, so no post-processing will be needed.
这将只返回出现在两个表中的用户名，因此不需要后期处理。
This construct is called an inner join. If you also want to identify usernames that are unique to table1and/or table2, you could use an outer join.
回答by Khaled.K
Pseudo-Code:
伪代码：
if ( A.type = B.type )
{
PRINT same type
if ( A.format = B.format )
{
PRINT same format
if ( A.value = B.value )
{
PRINT same value
}
else
{
PRINT different value
}
}
else
{
PRINT different format
}
}
else
{
PRINT different type
}
回答by Sarath Kumar Sivan
You can either solve it through SQL statement IN and NOT IN or you can try something like this:
您可以通过 SQL 语句 IN 和 NOT IN 解决它，也可以尝试这样的操作：
public boolean compareResultSets(ResultSet resultSet1, ResultSet resultSet2) throws SQLException{
while (resultSet1.next()) {
resultSet2.next();
ResultSetMetaData resultSetMetaData = resultSet1.getMetaData();
int count = resultSetMetaData.getColumnCount();
for (int i = 1; i <= count; i++) {
if (!resultSet1.getObject(i).equals(resultSet2.getObject(i))) {
return false;
}
}
}
return true;
}
回答by Akash5288
I am giving an example to solve this:
我举一个例子来解决这个问题：
rs1 = statement.executeQuery("select username from table1")
rs2 = statement.executeQuery("select username from table2")
while(rs1.next()) {
// Compare till rs1 reachs its last record.
while(rs2.next()) {
if() {
// Do your code here...
}
}
// this will move resultSet cursor to the first position.
rs2.first();
}
回答by vishal ajwani
One way could be:-
一种方法可能是：-
String query = "(" + query1 +") intersect ("+ query2 + ")";
Where in the intersect operation will anyway give you the common columns.
无论如何，相交操作中的何处都会为您提供公共列。
P.S. :- I know this question is old, but it might help somebody.
PS :- 我知道这个问题很老，但它可能对某人有所帮助。
