Question

请帮助!!!!!!! 在DB中，我有2行与此查询。

SELECT D.DEALER_CODE 
FROM SCOTT.T_DEALERSHIP D,SCOTT.T_DEALER_BILLING DB 
WHERE D.DEALER_CODE = DB.DEALER_CODE 
    AND DEALER_NAME LIKE 'XTIME%'
    AND (RNR_CUST_NUM = '546' OR RNR_CUST_NUM = '43356'OR RNR_CUST_NUM = '7637055' OR RNR_CUST_NUM ='7637055' OR RNR_CUST_NUM IS NULL) 
    AND (RCI_STORE_NUMBER IS NULL OR  RCI_STORE_NUMBER = '05')
    AND (RCI_AREA_NUMBER = '01'OR  RCI_AREA_NUMBER IS NULL) 
    AND (RCI_DEALER_NUMBER IS NULL AND DEALER_Address1 LIKE UPPER('1500 ORACLE%')                                
    AND DEALER_CITY =UPPER('BAKERSFIELD') AND DEALER_ZIP LIKE'6%')

使用下面的代码，当DB中有2条记录时，我只得到1行。当数据库中只有一条记录时，它可以工作，但是当有更多记录时则不行。此外，rs.last()方法也会被跳过并退出结果集。我必须评论它执行一个记录。我不想使用COUNT。

ResultSet rs = stmt.executeQuery(sql1);
System.out.println("" + sql1);

while(rs.next()) {
    rs.last();
    int Rows = rs.getRow();
    System.out.println("Rows are " + Rows);
}

Answer 1

如果您只想计算数据库中的记录，那么您应该使用SELECT count(*) FROM ...形式的查询。如果您确实需要按照上面列出的方式执行查询，那么您希望在while循环之外设置一个计数器变量，如下所示：

int rowNum = 0;
while (rs.next()) {
    rowNum++;
}
System.out.println("Number of records: "+rowNum);

Answer 2

我强烈建议不要通过JDBC将所有数据都返回给Java，以确定行数。如果您只想知道与条件匹配的行数，请执行select count（*）查询：

在SQL中：

SELECT COUNT(*)
FROM SCOTT.T_DEALERSHIP D,SCOTT.T_DEALER_BILLING DB
WHERE D.DEALER_CODE = DB.DEALER_CODE
    AND DEALER_NAME LIKE 'XTIME%'
    AND (RNR_CUST_NUM = '546' OR RNR_CUST_NUM = '43356'OR RNR_CUST_NUM = '7637055' OR RNR_CUST_NUM ='7637055' OR RNR_CUST_NUM IS NULL) 
    AND (RCI_STORE_NUMBER IS NULL OR  RCI_STORE_NUMBER = '05')
    AND (RCI_AREA_NUMBER = '01'OR  RCI_AREA_NUMBER IS NULL)
    AND (RCI_DEALER_NUMBER IS NULL AND DEALER_Address1 LIKE UPPER('1500 ORACLE%')
    AND DEALER_CITY =UPPER('BAKERSFIELD') AND DEALER_ZIP LIKE'6%')

然后在Java中：

ResultSet rs = stmt.executeQuery(sql1);
System.out.println("" + sql1);

int rows = 0;
if(rs.next()) {
    rows = rs.getInt();
}
System.out.println("Rows are " + rows);

根据OP的评论进行编辑

除了计数之外，要从数据库中获取值，只需扫描值。

SQL：

SELECT D.DEALER_CODE
FROM SCOTT.T_DEALERSHIP D,SCOTT.T_DEALER_BILLING DB
WHERE D.DEALER_CODE = DB.DEALER_CODE
    AND DEALER_NAME LIKE 'XTIME%'
    AND (RNR_CUST_NUM = '546' OR RNR_CUST_NUM = '43356'OR RNR_CUST_NUM = '7637055' OR RNR_CUST_NUM ='7637055' OR RNR_CUST_NUM IS NULL)
    AND (RCI_STORE_NUMBER IS NULL OR  RCI_STORE_NUMBER = '05')
    AND (RCI_AREA_NUMBER = '01'OR  RCI_AREA_NUMBER IS NULL)
    AND (RCI_DEALER_NUMBER IS NULL AND DEALER_Address1 LIKE UPPER('1500 ORACLE%')
    AND DEALER_CITY =UPPER('BAKERSFIELD') AND DEALER_ZIP LIKE'6%')

爪哇：

ResultSet rs = stmt.executeQuery(sql1);
System.out.println("" + sql1);

List<String> rows = new ArrayList<String>();
while(rs.next()) {
    rows.add(rs.getString());
}
System.out.println("There are " + rows.size() + " rows.");

使用结果集获取行数

2 个答案: