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String query = "SELECT sum(Cardhundred)FROM Dialog"; [duplicate]

This question already has an answer here:
How to retrieve sum of a column of data from the database?
(1 answer)
Closed 4 years ago.
Currently trying to get sum of the integers of a column called Cardhundred, I does not proceed the answer, can somebody suggest me an idea to get the total of all integers in my column?
I want to get the sum from a column in access database, the column from which I want to get the sum, has all integers value not double or float, and I have done some code for that which gives me no result, it means the text field which supposed to display the result is empty.
This is my code:
if(showtotal.isSelected()) {
try {
Connection conn = DriverManager.getConnection("jdbc:ucanaccess://E:\\Mydb.accdb");
Statement st = conn.createStatement();
String query = "SELECT sum(Cardhundred)FROM Dialog";
ResultSet rs=st.executeQuery(query);
if(rs.next()) {
String total=rs.getString("sum(Cardhundred)");
showdate.setText(""+total+"");
}
} catch(Exception e){ }
}

There are two ways to solve this: use the column index (rather than the name) then you don't need to worry about the name of the expression:
int total = rs.getInt(1);
The column numbering in JDBC starts with 1, not with 0 as with arrays in Java.
Alternatively, use a column alias in your query:
String query = "SELECT sum(Cardhundred) as total_number FROM Dialog";
Then use that alias to get the value:
int total = rs.getInt("total_number");

Efficient way to compare input Data with Sql table in Java

First of all I will explain my use case:
I will get a String Array of names from user(Can of size 2,5,1)
e.g Suppose user input is like this:
String[] names={"Micheal", "Joe","Jim"}
Now after taking input from user, I have to hit SQL table called "USERS" and check whether all of these names are present in USERS table or not. If any single name is not present then return false. If all names are present in USERS table then return true.
My Idea:
My idea is to hit USERS table. Get all names of USERS table in a String array (named as all_names) and then compare my input string(i.e names) with this all_names String. So if names is subset of all_names then return true else return false.
Problem:
But I think this is not an efficient solution. When this table will expand then I will have thousands of records so this technique will be very exhaustive. Any other better and efficient solution for this please.
Updated Solution:
Suppose names in USERS table are unique.
Thanks for your replies. Now I have adopted this approach after getting help from your answers. I want to know that this solution is a better approach or not:
String[] names={"Micheal","Jim","Joe"};
String list2string = StringUtils.join(names, ", ");
//connection was established previosuly
stmt = conn.createStatement();
System.out.println(list2string);
rs = stmt.executeQuery("SELECT COUNT(*) AS rowcount FROM USERS WHERE name IN (" +
list2string +
")");
rs.next();
int count = rs.getInt("rowcount");
rs.close();
if(names.length==count){
System.out.println("All names are in users table");
}else{
System.out.println("All names are not present in users table");
}
Want your comments on this updated solution please.
Regards

You are right, this is not really efficient.
It is the database job to do such things.
You can either make a select statement for each name, eg.
SELECT name FROM users WHERE name = 'Micheal'
or
SELECT name FROM users WHERE name IN ('Micheal', 'Joe', 'Jim')
and check the returned rows.
It might be quiet different depending on which framework you use to query the database.

you can form a string out of string array using loop
for example if you have string array like this:
String[] names={"Micheal", "Joe","Jim"}
get a string lets say s -> "Micheal", "Joe","Jim"
now query like this:
String sql = SELECT name FROM users WHERE name IN (" + s + ")". (you can check the format).
get the output collection and compare with the given collection.

One way to do it, could be
SELECT
COUNT(DISTINCT name)
FROM
users
WHERE
name IN ('Micheal', 'Joe', 'Jim')
Then check if the count is equal to your parameter count, in our case, we should get 3.

I will get a String Array of names from user(Can of size 2,5,1)
You get the input from user, you hit the database with query:
SELECT (WHATEVER_YOU_NEED) FROM SCHEMA_NAME.TABLE_NAME WHERE COLUMN IN
(USER_PROVIDED_INPUT);
You store this result in List.
Get all names of USERS table in a String array (named as all_names)
and then compare my input string(i.e names) with this all_names
String. So if names is subset of all_names then return true else
return false.
Yes, you are right, so you will use
Use Collection.containsAll():
boolean isSubset = listA.containsAll(listB);
And, if your database has unique names (which I guess can be duplicate), you can simply get the count from SQL Query and match it with the user input.
I hope this will help.

SELECT IF(
( SELECT COUNT(DISTINCT name) FROM users WHERE name IN ({toSearch}) ) = {Count},
, 1 , 0
) as Result
replace {toSearch} with e.g. 'Micheal', 'Joe', 'Jim'
{count} is the number of searche, in this example 3. so if all exist the column "Result" has the value 1 else 0

How to print a MAX and a description from Java Database

I'm beginning to learn about connecting to databases via Java programs. I have a table called City, which contains just two columns: CityName and Population. I want to find the highest population, and then give that population along with the name of the corresponding city.
I know how to get just the highest population (see the following, which I know is probably not ideal but at least is working for me):
double max = 0.0;
String sqlStatement = "SELECT MAX(Population) FROM City";
ResultSet result = stmt.executeQuery(sqlStatement);
if (result.next())
{
highest = result.getDouble(1);
}
System.out.printf("Highest population: %,.0f", highest);
I am pretty sure that to get the highest population PLUS the name of the corresponding city, my Sql statement should eb changed to :
"SELECT CityName, MAX(Population) FROM City GROUP BY CityName";
But I can't get it to work beyond that. I thought I could add something like
String highestCity = result.getString(2)
and then add highestCity to the System.out.printf output line, but that isn't working.
Can anyone help?
Thanks!

How about this ?
String sqlStatement = "SELECT CityName, Population FROM City WHERE Population IN (SELECT MAX(Population) FROM City)";

You want to sort your results by population descending, and limit your query to only return one result. Something like:
SELECT * FROM city ORDER BY population DESC LIMIT 1;

How can i get another string from select query?

I want to get string from column no. 4 from my database to check user privileges.
Can I use rs.getString(index) to get data from column no.4?
I want to check user´s privileges...so if the column data is equal 4, the page will be redirected to AdminControlPanel.jsp
BUT, this code doesn´t work :(
String user=request.getParameter("login");
String pass=request.getParameter("password");
Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/android","root","root");
Statement st=con.createStatement();
ResultSet rs=st.executeQuery("select * from users where login='"+user+"' and password='"+pass+"'");
String p = rs.getString(4);
int count=0;
while(rs.next()){
count++;
}
if(count>0 && p == "4"){
// out.println(rs);
response.sendRedirect("AdminControlPanel.jsp");
}
else{
out.println("aaa");
response.sendRedirect("#");
}
}
catch(Exception e){
System.out.println(e);
}

you are comparing two String objects rather than checking the values in the String.
just change the code to p.equals("4") and try.

String p = rs.getString(4); // This should be inside your while
int count=0;
while(rs.next()){
count++;
}
You should move your first line inside your while loop. You can't
fetch the columns of a row, until you move your cursor to that row
using res.next().
Also, since your database should ideally have only one record for a
combination of username and password. So, you can better use an
if instead of while.
And you don't really need a count variable there.
So, your code should be: -
ResultSet rs=st.executeQuery("select * from users where login='"+user+"' " +
"and password='"+pass+"'");
if (rs.next()) {
String p = rs.getString(4); // Note that using Column name is a better idea
// or rs.getInt(4) if the column type is `int`
if(p.equals("4")) { // Use equals method to compare string content
response.sendRedirect("AdminControlPanel.jsp");
} else{
out.println("aaa");
response.sendRedirect("#");
}
}
Also, note that you should compare your string using equals method. if (p == "4") will give you false result. == operator does not compare the content of the string, rather the content of the reference used in comparison.

You want
while (rs.next()) {
String val = rs.getString(4);
....
Note that iterating through a ResultSet iterates through the rows. For each row, the column indexing starts from '1'.
However it's safer to get by column name, since your SQL query doesn't specify neither the columns nor the order in which they're returned:
String val = rs.getString("COLUMN_NAME");
I see from the below that you need an integer. Check out the doc for ResultSet for more info, but:
int val = rs.getInt("COLUMN_NAME");
As an aside, I don't see you closing your ResultSet/Statement/Connection in the above. If you're not, then you'll need to!

java.lang.IndexOutOfBoundsException: Index: 4, Size: 4

How can I fix this OutOfBoundsException?
Here is the code I am using:
ResultSet rsTagCheck = stmt.executeQuery(
"SELECT PARKING.XKRPRMT.XKRPRMT_PIDM, PARKING.XKRPRMT.XKRPRMT_STATUS, PARKING.XKRPRMT.XKRPRMT_EXPIRE_YR, PARKING.XKRPRMT.XKRPRMT_TAG FROM PARKING.XKRPRMT WHERE XKRPRMT_PIDM ='" + BannerID + "'");
while (rsTagCheck.next()){
String TagNum = rsTagCheck.getString("XKRPRMT_TAG");
ArrayList<String> myTag = new ArrayList<String>();
for (int i = 0; i < TagNum.length(); i++){
myTag.add(TagNum);
myTag.get(i + i);
I kinda know why I am getting the error, but I am not sure how to remedy the problem.

The problem is the i+i part in myTag.get(i+i). It'll work for i=0, but as soon as i=1, you'll get an exception thrown, since you've added two elements to myTag, but are accessing the third element (myTag.get(2)).

What is it that you expect myTag.get(i + i) to do?
The first time through the loop, "i" is zero and you add one element. There won't be an element 1, so the call will throw an exception. Now that I actually see what you wrote, it'll fail on the second iteration, not the first, as poor #Giu noted in his now-deleted answer. Still, it's weird and I don't know what you're trying to accomplish by calling .get() and not even looking at the return value.
You really will have to explain what it is you're trying to do, because that doesn't really make any sense as written. Did the exception in the question title really come from that code, or did you edit part of it out when posting?
edit — whoops totally saw "i+i" as "i+1". Still makes no sense to me however.

You are using the for loop by iterating on the String TagNum. You should only need to say: myTag.add(TagNum).
Imagine that the String TagNum has 4 characters. You add the String to the list 4 times, but when you reach i = 3, you are trying to retrieve the element at position 3 + 1, but the list has elements from 0 to 3.
Also, try replacing the BannerID with a ? and set the parameter to the statement accordingly.

This myTag.get(i + i); is causing the exception.
First time in the loop i is 0, you add an item into the ArrayList and then call get(0+0) which is fine.
In the next iteration, you add another element(total of 2 element in the list now) and call get(1+1), this causes exception as you have only 2 elements and valid index are 0 and 1.

Even without the problem with the get, your program as written will read through the results of the query, and then for each CHARACTER in tagNum, it will add an instance of tagNum to your array. So if tagNum is, say, "ABC", the array will end up containing "ABC" three times. If tagNum is "ABCD", it will contain "ABCD" four times. This doesn't make a lot of sense.
I think what you want is to just add tagNum to an array, defining the array OUTSIDE of the ResultSet.next loop. Something like this maybe:
ArrayList<String> myTag = new ArrayList<String>();
ResultSet rsTagCheck = stmt.executeQuery(
"SELECT PARKING.XKRPRMT.XKRPRMT_PIDM, PARKING.XKRPRMT.XKRPRMT_STATUS, PARKING.XKRPRMT.XKRPRMT_EXPIRE_YR, PARKING.XKRPRMT.XKRPRMT_TAG FROM PARKING.XKRPRMT WHERE XKRPRMT_PIDM ='" + BannerID + "'");
while (rsTagCheck.next()){
String TagNum = rsTagCheck.getString("XKRPRMT_TAG");
myTag.add(TagNum);
}
(Of course this doesn't use any of the other data in your query and I don't know what all else you're up to, but I believe that's what you're trying to do for this part.)
Update
Suppose you have ten records in your database table. After the above loop is complete, the array should be populated.
Try something like this:
ArrayList<String> myTag = new ArrayList<String>();
ResultSet rsTagCheck = stmt.executeQuery(
"SELECT PARKING.XKRPRMT.XKRPRMT_PIDM, PARKING.XKRPRMT.XKRPRMT_STATUS, PARKING.XKRPRMT.XKRPRMT_EXPIRE_YR, PARKING.XKRPRMT.XKRPRMT_TAG FROM PARKING.XKRPRMT WHERE XKRPRMT_PIDM ='" + BannerID + "'");
while (rsTagCheck.next()){
String TagNum = rsTagCheck.getString("XKRPRMT_TAG");
myTag.add(TagNum);
}
for (String tag : myTag)
{
System.out.println(tag);
}
That should give you the list of all the tags. Note you have to examine the List AFTER the while(ResultSet) loop ends. Inside the loop you will only have the elements read so far.
If you're still getting only one value, make sure that you have more than one record coming back from the result set. Like, run the query outside of a Java program and see how many records you get.

List<WebElement> div1=driver.findElements(By.xpath(".//*[#class='art_title']"));
for(int i=0;i<=div1.size();i++)
{
System.out.println(div1.get(i).getText());
Thread.sleep(1000);
}
Instead of the above format I changed it into this format :
List<WebElement> div1=driver.findElements(By.xpath(".//*[#class='art_title']"));
String[] abc = new String[div1.size()];
int i= 0;
for (WebElement e : div1)
{
abc[i] = e.getText();
i++;
System.out.println(e.getText());
}