Category: Databases

What are some ways to improve MySQL performance on queries against large tables that include the HAVING BY clause. It's my understanding that anything in there doesn't benefit from table indexes.

This is the error message:

%Run -c $EDITOR_CONTENT
Traceback (most recent call last):
File "<string>", line 6
image = cv2.imread(C:\Users\Audun Nilsen\Pictures\pica.webp)
^
SyntaxError: invalid character in identifier

This is the code:

import cv2 # OpenCV for image processing

image = cv2.imread(C:\Users\Audun Nilsen\Pictures\pica.webp)

How do I create a table in postgres that's associated with a specific database?

Obviously from the command line one can do

Create table tablename ();

But how do I make sure that the table is associated with the correct database?

CREATE table dbname.tablename();

is giving me the error:

ERROR:  schema "dbname" does not exist

My textbox datatype is DateTime.

Using the click event of a button, this code is placed following MyTableBindingSourceAddNew()

Dim CurrentDateTime As DateTime = DateTime.Now.ToString("dd.MM.yy hh:mm:ss")
Me.SaleDateTextBox.Text = CurrentDateTime

I then update table with TableAdapter.

On my form I have a dropdown combobox in a toolbar, display member being "SaleDate"
This displays DateTime, but time is always 12:00:00AM
The SaleDateTextbox.Text populates as Date.Now.

I am not getting correct date and time in both textbox and combobox.

All help appreciated.

Shane.

I'm working on an SQL query for a complex reporting system that involves multiple tables and joins. However, the query's performance is not meeting my expectations, and I suspect that the way I've structured my joins might be inefficient.

Here's a simplified version of my query:

SELECT
    orders.order_id,
    customers.customer_name,
    products.product_name,
    order_details.quantity,
    order_details.unit_price
FROM
    orders
JOIN
    customers ON orders.customer_id = customers.customer_id
JOIN
    order_details ON orders.order_id = order_details.order_id
JOIN
    products ON order_details.product_id = products.product_id
WHERE
    orders.order_date BETWEEN '2023-01-01' AND '2023-12-31';

While this query returns the correct results, it's taking a significant amount of time to execute, especially when dealing with a large dataset.

I'd like to optimize this query for better performance. Could someone review my SQL code and suggest improvements or alternative approaches to achieve the same result more efficiently? Additionally, are there any indexing strategies or database design considerations that might help enhance the query's speed? Any insights or code optimizations would be greatly appreciated. Thank you!

An equipment company wishes to create a database to support the hiring of tools and machinery to clients. The company has three types of equipment: power tools, such as drills and vacuum cleaners, plants such as excavators and scaffolding. Each piece of equipment is identified by a number. Power tools are described by their model and the voltage they use, whereas plants are classified by their model and their size tonnes. can be traditional, aluminium fibreglass; in addition, its width can be single or double. A large piece of equipment may be composed of smaller pieces of equipment.

The company has various outlets and each has staff including a manager and several senior technicians who are responsible for supervising the work of allocated groups of technicians. A supervision record is also kept for a specific date. All employees are identified by their number, name, date of birth (DOB) and address. Furthermore, a record is kept on their employment records and their qualifications.

Each outlet has a stock of equipment that may be hired by clients for varying periods of time, from a minimum of four hours to a maximum of six months. Each hire agreement between a client and the company is uniquely identified by using a hire number. Each client is identified by a number and a name. The company insists that each client must take out insurance cover for each equipment hire period. Each insurance cover is identified by a unique insurance number and includes the description of the insurance. The company wishes to keep a record of the member of staff who was in charge of a specific hire agreement. Each piece of equipment is checked for faults when it is returned by the client, and the faults/defects/damage recorded. The company keeps a record of the hire history of each client.

1. Create an ER diagram for the above scenario and indicate the cardinality of relationships and the nature of the associations (mandatory or optional). You should allocate adequate attributes to the entities of interest, especially the identifiers.

i have 3 tables : users, deposit, withdraw
table users :

id , username, referral

1. 1, a1, null
2. 2, a2, a1
3. 3, a3, a2
4. 4, a4, a1
5. 5, a5, a2

table deposit :

id, users_id, amount, status, approve_date

1. 1, 1, 10000.00, approve, 2022-10-01 14:52:53
2. 2, 3, 10000.00, approve, 2022-10-01 14:52:53
3. 3, 3, 10000.00, approve, 2022-10-01 14:52:53
4. 4, 3, 10000.00, approve, 2022-10-01 14:52:53
5. 5, 5, 10000.00, approve, 2022-10-01 14:52:53

table withdraw :

id, users_id, amount, status, approve_date

1. 1, 1, 20000.00, approve, 2022-10-01 14:52:53
2. 2, 3, 10000.00, approve, 2022-10-01 14:52:53
3. 3, 3, 30000.00, approve, 2022-10-01 14:52:53
4. 4, 3, 40000.00, approve, 2022-10-01 14:52:53
5. 5, 5, 100000.00, approve, 2022-10-01 14:52:53

I would like to have the below end result, how do I combine the 3 tables together? The end result is sorted by SUM(deposit.amount) SUM(withdraw.amount) and where by approve date and search by referral . I apologize for couldn't display table data in a nice format for easier viewing. Thank you for your help.
what is try is like this sql code :

SELECT a.`referral`, a.`id`, a.`username`, SUM(b.`amount`) AS Total,SUM(c.`amount`) AS Totals FROM users a 
LEFT JOIN  `deposit` b ON a.`id` = b.`user_id` 
LEFT JOIN  `withdraw` c ON a.`id` = c.`user_id` 
WHERE 1
AND b.`approve_date` >= '2022-10-01 00:00:00' 
AND b.`approve_date` <= '2022-11-04 23:59:59' 
AND b.`status` = 'approve'
AND c.`status` = 'approve'
AND a.`referral` = 'a1' 
GROUP BY b.user_id,c.user_id
ORDER BY a.`id` DESC 
LIMIT 500 OFFSET 0

the result i want is like this:

username, total_deposit, total_withdraw

1. a3, 30000, 80000

The job youre applying for says, Redis experience required. Are you ready for the questions a hiring manager is likely to ask? Heres how to prepare for the job interview... as inspired by Lord of the Rings.

Nominally the article is written for someone getting answers ready for Redis-specific questions, but I think they'd apply for any database-related job. Especially if you have experience with one tool and the job asks for experience with another.

Hello all,

I would like to set a time after 2 requests that someone can make a request again does anyone have an example for this.

thanks in advance

What is the difference between openGauss and postgresql in the key technologies?Can you elaborate on this from the following points (including but not limited to): runtime model, transaction mechanism, data storage and organization, query optimizer, etc.

hello, i hope someone can help me i have a table ip in my database if there is 5 times in it he has to forward it in php to another page.

thanks in advance

Hello , i am using vb6.0 can some one help me with my problem. I want to summarize a database with multiple name and display it into one data where the date is same today. thank you for any one would response.

for example. below is a table where multiple names created.

In database

Name            Total Payment           Date
lius--             100---               07/01/22
lius--             100---               07/01/22
lius--             50--                 07/01/22 
era--              60--                 07/03/22
era--              50--                 07/03/22

So when it executed in listview form it would look like on the below sample

Name            Total Payment           Date
lius--             250--                07/01/22
era--              110--                07/03/22

Here is my code for executing my database in listview form

Set rxb = New ADODB.Recordset
rxb.Open "Select * from History order by trn", con, 3, 3

with rxb
    On Error Resume Next
    Do While Not .EOF
        ListView2.ListItems.Add , , !TRN, 1, 1
        ListView2.ListItems(ListView2.ListItems.count).SubItems(1) = "" & !Emp
        ListView2.ListItems(ListView2.ListItems.count).SubItems(3) = "" & !hdate
        ListView2.ListItems(ListView2.ListItems.count).SubItems(4) = "" & !htime
        ListView2.ListItems(ListView2.ListItems.count).SubItems(5) = "" & !purchases
        ListView2.ListItems(ListView2.ListItems.count).SubItems(6) = "" & !payment
        ListView2.ListItems(ListView2.ListItems.count).SubItems(7) = "" & !rBalance
        ListView2.ListItems(ListView2.ListItems.count).SubItems(8) = "" & !adjustment
        ListView2.ListItems(ListView2.ListItems.count).SubItems(9) = "" & !Pm
        ListView2.ListItems(ListView2.ListItems.count).SubItems(10) = "" & !Cashier
        .MoveNext
    Loop
    .Close
End With

import net.proteanit.sql.DbUtils;

import javax.swing.*;
import javax.xml.transform.Result;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.sql.*;

public class EmployeeRegistriation {
    private JPanel Main;
    private JTextField txtName;
    private JTextField txtSalary;
    private JTextField txtMobile;
    private JButton saveButton;
    private JTable table1;
    private JButton updateButton;
    private JButton deleteButton;
    private JButton searchButton;
    private JTextField txtId;
    private JScrollPane tabla_1;

    public static void main(String[] args) {
        JFrame frame = new JFrame("EmployeeRegistriation");
        frame.setContentPane(new EmployeeRegistriation().Main);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setVisible(true);
    }
    Connection con;
    PreparedStatement pst;

     public void connect()
    {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            con = DriverManager.getConnection("jdbc:mysql://localhost/johnrichescompany", "root", "");


            System.out.println("Success");


        }
        catch (ClassNotFoundException ex)
        {
            ex.printStackTrace();

        }
        catch (SQLException ex)
        {
            ex.printStackTrace();
        }
    }

    private void forName(String s) {
    }


    public EmployeeRegistriation() {
        connect();
        table_load();

        saveButton.addActionListener(new ActionListener() {

            /**
             * Invoked when an action occurs.
             *
             * @param e the event to be processed
             */
            @Override
            public void actionPerformed(ActionEvent e) {

                String empname, salary, mobile;


                empname = txtName.getText();
                salary = txtSalary.getText();
                mobile = txtMobile.getText();


                try {
                    pst = con.prepareStatement("insert into employee_registration(empname,salary,mobile)values(?,?,?)");
                    pst.setString(1, empname);
                    pst.setString(2, salary);
                    pst.setString(3, mobile);
                    pst.executeUpdate();
                    JOptionPane.showMessageDialog(null, "Record Added!!!");
                    table_load();
                    txtName.setText("");
                    txtSalary.setText("");
                    txtMobile.setText("");
                    txtName.requestFocus();
                } catch (SQLException ex) {
                    ex.printStackTrace();
                }

            }
        });
        searchButton.addActionListener(new ActionListener() {
            /**
             * Invoked when an action occurs.
             *
             * @param e the event to be processed
             */
            @Override
            public void actionPerformed(ActionEvent e) {
                try {
                    String employeeid = txtId.getText();

                    pst = con.prepareStatement("select empname, salary, mobile from employee_registration where employeeid = ?");
                    pst.setString(1, employeeid);
                    ResultSet rs = pst.executeQuery();

                    if (rs.next() == true) {
                        String empname = rs.getString(1);
                        String salary = rs.getString(2);
                        String mobile = rs.getString(3);


                        txtName.setText(empname);
                        txtSalary.setText(salary);
                        txtMobile.setText(mobile);


                    } else {
                        txtName.setText("");
                        txtSalary.setText("");
                        txtMobile.setText("");
                        JOptionPane.showMessageDialog(null, "Invalid Employee Id");
                    }
                } catch (SQLException ex) {
                }
            }
        });
        updateButton.addActionListener(new ActionListener() {
            /**
             * Invoked when an action occurs.
             *
             * @param e the event to be processed
             */
            @Override
            public void actionPerformed(ActionEvent e) {

                String employeeId, empname, salary, mobile;


                empname = txtName.getText();
                salary = txtSalary.getText();
                mobile = txtMobile.getText();
                employeeId = txtId.getText();


                try {
                    pst = con.prepareStatement("update employee_registration set empname = ?,salary + ?,mobile = ? where employeeId =?");
                    pst.setString(1, empname);
                    pst.setString(2, salary);
                    pst.setString(3, mobile);

                    pst.executeUpdate();
                    JOptionPane.showMessageDialog(null, "Record Updated!!!");
                    table_load();
                    txtName.setText("");
                    txtSalary.setText("");
                    txtMobile.setText("");
                    txtName.requestFocus();


                } catch (SQLException e1) {
                    e1.printStackTrace();
                }


            }
        });
        deleteButton.addActionListener(new ActionListener() {
            /**
             * Invoked when an action occurs.
             *
             * @param e the event to be processed
             */
            @Override
            public void actionPerformed(ActionEvent e) {
                String employeeid;



                employeeid = txtId.getText();




                try {
                    pst = con.prepareStatement("delete from employee_registration where employeeid = ?");
                    pst.setString(1, employeeid);
                    JOptionPane.showMessageDialog(null, "Record Deleted!!!");
                    table_load();
                    txtName.setText("");
                    txtSalary.setText("");
                    txtMobile.setText("");
                    txtName.requestFocus();

                }
                catch (SQLException e1) {
                    e1.printStackTrace();
                }








            }
        });
    }

    void table_load() {
            try {
                pst = con.prepareStatement("select * from employee_registration");
                ResultSet rs = pst.executeQuery();
                table1.setModel(DbUtils.resultSetToTableModel(rs));
            }
            catch (SQLException e)
            {
                e.printStackTrace();
            }












    }




}

so we were trying to make a simple log in form and our professor simply told us to copy the codes he wrote:

i copied it but i got a red line under line 20 and 21 . I dont know what to do, no one is responding to me in the class and my professor never responded when he saw my question. here is the whole code if you cant see it whole in the picture:

There are 2 tables as orders$ and 'order items$'
orders$ Table have 4 columns as order_id, customer_id, status, order_date
'order items&' Table have 4 columns as order_id, item_id, product_id, quantity

I want to modify the SQL statement to show an average number of products each customer had on their orders.

SELECT DISTINCT (c.customer_id) AS CustomerID, o.order_id AS OrderID, AVG(o.product_id)AS AvgProductOrdered
FROM orders$ c
INNER JOIN ['order items$'] o ON c.order_id = o.order_id
WHERE c.order_id = o.order_id
GROUP BY c.customer_id, o.order_id
ORDER BY AvgProductOrdered

hii how can i make self join and sum data in other table by username
i have table like this

members (id, username, referral)
ref_bonus (id, username, bonus)

members
id  | username | referral
----------------------
1    id1        id2
2    id2        null
3    id3        id2

ref_bonus
id | username | bonus
----------------------
11    id2      1.00
21    id2      1.00
31    id2      1.00

the result i want is select all member have referral and sum bonus in ref_bonus
example result is like this :

id  | username | count_ref | sum_bonus
----------------------
1    d2          2         | 3.0

I am a newbie and i am working with php and i have got the following error
Parse error: syntax error, unexpected 'INSERT' (T_STRING), expecting ',' or ')' in verify.php on line 9
CODE SNIPPET: