Question

下面我展示了我在Java中动态的SQL查询。

Calendar cal = Calendar.getInstance();
cal.add(Calendar.DAY_OF_YEAR, -365);

调整到当月之前的12个月，0小时和分钟

cal.set(cal.get(Calendar.YEAR), cal.get(Calendar.MONTH), 1, 0, 0, 0);
String lastYearTime = String.valueOf(cal.getTimeInMillis() / 1000);

while(iterator.hasNext())
    {
        tablename = Database.getTableName((String)iterator.next());
        fields = "status,count(*) as count";
        query.append("select " + fields + " from " + tablename + " where");
        query.append(" toid ='" + collegeId + "'");
        query.append(" and dtstamp >='" + lastYearTime + "'");
        query.append(" group by status");
        if(i.hasNext())
            query.append(" UNION ");
    }
    StringBuffer countquery = new StringBuffer("select status, SUM(count) as count from ( " + query + ")as temp  group by status ");

    ResultSet rs = Database.executeQuery(countquery.toString(), connection);

在上面的查询中，tablename将根据其他因素随机显示。 collegeId可以是任何id。状态可以是辍学，追求或任何随机状态。

当我执行上面的查询时，结果集工作正常并显示数据。但是当数据库中没有记录时，它会抛出一个sql语法错误1064，说明

您的SQL语法有错误;检查与您的MySQL服务器版本相对应的手册，以获得正确的语法，以便在状态＆＃39;）附近使用临时组。在第1行

Answer 1

<强>问题1

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ')as temp  group by status' at line 1

您的查询中存在问题：

select status, SUM(count) as count from ( " + query + ")as temp  group by status

您应该在查询中留出空格：

from ( " + query + ")as

将此")as替换为此") as

修改

<强> Problem2

SQL Exception : You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ') as temp group by status' at line 1 SQL State : 42000 Error Code : 1064

您的查询为String，因此您应将其置于两个'query'
之间
现在替换它：

select status, SUM(count) as count from ( " + query + ")as temp group by status

由此：

select status, SUM(count) as count from ( '" + query + "') as temp group by status
祝你好运。

Answer 2

当数据库中没有记录时，Resultset会引发语法错误

不，不。当您的查询中出现语法错误时，它会抛出语法错误异常。

当数据库中没有记录时，Resultset会引发语法错误

2 个答案: