MySQL 在返回的mysql结果中查找行数（nodejs）
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find number of rows in returned mysql result (nodejs)
提问by Huckle
When using felixge's mysql for node.js, how can I ask the result object for the number of returned rows? I have a rather expensive query so I don't want to run a COUNT(*)first, just to then run a query a second time.
node.js使用felixge的mysql时，如何向结果对象查询返回的行数？我有一个相当昂贵的查询，所以我不想运行COUNT(*)第一个，只是为了第二次运行查询。
回答by Daniel
If it's a select query, just take the length of the returned array.
如果是选择查询，只取返回数组的长度。
connection.query(sql, [var1,var2], function(err, results) {
numRows = results.length;
});
If it's an update/delete query, the returned dictionary will have an affectedRows variable.
如果是更新/删除查询，则返回的字典将有一个受影响的行变量。
connection.query(sql, [var1,var2], function(err, result) {
numRows = result.affectedRows;
});
回答by rdcapasso
If you're using the examples in the readme just look at the length property of the rows object (i.e. rows.length).
如果您使用自述文件中的示例，只需查看行对象的长度属性（即rows.length）。
回答by vkhazin
With the version of mssql 2.1.2 as of 2015-04-13:
使用 2015-04-13 的 mssql 2.1.2 版本：
delete from DeviceAccountLinks where DeviceAccountId = @deviceAccountId and DeviceType = @deviceType
从 DeviceAccountLinks 中删除，其中 DeviceAccountId = @deviceAccountId 和 DeviceType = @deviceType
statement will produce no results as 'undefined'
语句不会产生“未定义”的结果
I have changed the statement to:
我已将声明更改为：
delete from DeviceAccountLinks where DeviceAccountId = @deviceAccountId and DeviceType = @deviceType; select @@rowcount "rowCount"
从 DeviceAccountLinks 中删除，其中 DeviceAccountId = @deviceAccountId 和 DeviceType = @deviceType；选择@@rowcount "rowCount"
to get the output of: [{rowCount:1}]
得到输出：[{rowCount:1}]
