How to find the length of a particular column of a table in javascript?

问题

I am using sqlite database in my project.

My table structure will be almost like this

id  cid values

1   1   value1
2   1   value2
3   1   value3
4   1   value4
5   2   value1
6   2   value2
7   3   value1
8   3   value2
9   3   value3

so I want all the values of the same cid,how should I code it?

My query:

tx.executeSql("SELECT cid,value FROM table where cid="+cid_value, [], querySuccess, errorCB,cid_value);

because,when I tried it the following manner,

var details = results.rows.length;
console.log("db test value:"+results.rows.item(cid_value).value);
for (var i=cid_value; i<details; i++)
{
cidinstance=results.rows.item(i).cid;
var valueinstance=results.rows.item(i).value;
document.getElementById("s"+i+"cause").innerHTML=valueinstance;
console.log("cid= "+cidinstance +   "valueinstance= "+valueinstance);
}

then when i=cid_value(cid_value=1) targeting cid=1, where we have four values I get just 3 values.but,if i put i=0,then I get 4 values

when i=cid_value(cid_value=2) targeting cid=2,i get the following

01-01 05:45:38.687: I/Web Console(2425): JSCallback: Message from Server:  SQLitePluginTransaction.queryCompleteCallback('1104538538488000','1104538538491000', [{"value":"value1","cid":"2"},{"value":"value22","id":"6","cid":"2"}]); at file:///android_asset/www/cordova-2.1.0.js:3726.

The Problem is,I am getting the values when I get the message from the server as JS Callback. not from the for loop

Please,suggest me ways to solve the problem!.guide me to find a way out.

回答1:

If you want to find the number of rows where a particular CID is listed, you need to use the COUNT function in SQLite.

So your statement would be ::

SELECT COUNT(values) FROM TableName WHERE cid=1

That will give you the count directly. You don't need any code to do the calculations yourself.

来源：https://stackoverflow.com/questions/16649454/how-to-find-the-length-of-a-particular-column-of-a-table-in-javascript

标签

javascript

jquery

sqlite