未找到 java.sql.sqlexception 列
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java.sql.sqlexception column not found
提问by Dilini
I am trying to find max no from tr_id (primary key) in transaction table.
Here is the table and it's layout. 
我正在尝试从事务表中的 tr_id（主键）中找到 max no。
这是桌子和它的布局。
Here is my cord.
这是我的绳子。
try {
ResultSet rs = db.getData("SELECT MAX(tr_id) FROM transaction");
ResultSetMetaData meta = rs.getMetaData();
for (int index = 1; index <= meta.getColumnCount(); index++) {
System.out.println("Column " + index + " is named " + meta.getColumnName(index));
}
if (rs.first()) {
int tr_id = rs.getInt("tr_id");
}
I'm using JDBC connection. When I'm running this cord I'm getting this error.
我正在使用 JDBC 连接。当我运行这条线时，我收到了这个错误。
Column 1 is named MAX(tr_id)
java.sql.SQLException: Column 'tr_id' not found.
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:910)
at com.mysql.jdbc.ResultSet.findColumn(ResultSet.java:955)
at com.mysql.jdbc.ResultSet.getInt(ResultSet.java:2570)
at Controler.InvoiceFinalising.saveInvoice(InvoiceFinalising.java:57)
etc..
The thing is when I'm searching out as "tr_id" column name goes to Max(tr_id)
问题是当我搜索“tr_id”列名到 Max(tr_id)
采纳答案by Sanjeev
This is because the column name in your sql query is max(tr_id). You can write it as
这是因为您的 sql 查询中的列名是 max(tr_id)。你可以把它写成
ResultSet rs = db.getData("SELECT MAX(tr_id) as tr_id FROM transaction");
now you will be able to get it.
现在你将能够得到它。
