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Why does the same exact query produce 2 different MySQL explain results?


Why does the same exact query produce 2 different MySQL explain results?

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Why does the same exact query produce 2 different MySQL explain results?
Tag : mysql , By : meodudang
Date : November 28 2020, 08:01 AM


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Mysql query should produce results, but doesn't


Tag : php , By : Saurabh
Date : March 29 2020, 07:55 AM
wish of those help Remove the '%' characters around "$trimmed" in the first query.
See if that fixes it.

Trying to understand EXPLAIN results of query in mySQL


Tag : mysql , By : AJacques
Date : March 29 2020, 07:55 AM
hop of those help? Here is the fiddle for you: http://sqlfiddle.com/#!2/a6224/2/0
As @Daniel already said, MySQL takes into account not only indices, but also the number of rows in each table. The number of rows is low both in my fiddle and in your database - so it is hard to blame MySQL.

Why does my mysql query takes way too long to produce results


Tag : php , By : Alecsandru Soare
Date : March 29 2020, 07:55 AM
I hope this helps you . Without knowing how your database is set up and indexed, and what table storage engines you are using, I can only guess as to why its slow.
Your first query could return multiple rows consisting of table names You run 4 simple select statements. You run an insert with a select statement. The select query here also joins 3 tables together

MySQL/PHP - Need to be able to produce query results with certain columns having more weight than others


Tag : php , By : akr
Date : March 29 2020, 07:55 AM
I wish this helpful for you Bear with me, this is going to be a strange query, but it seems to work on my end.
SELECT SUM(
  IF(year = "1968", 30, 0) +
  IF(make = "Ford", 100, 0) +
  IF(model = "Mustang", 85, 0) +
  IF(color = "Red", 10, 0) +
  IF(type = "Sports Car", 50, 0)
) AS `weight`, cars.* FROM cars 
  WHERE year = "1968" 
  OR make = "Ford"
  OR model = "Mustang"
  OR color = "Red"
  OR type = "Sports Car"
GROUP BY cars.id
ORDER BY `weight` DESC;
+============================================================+
| weight | year | make      | model    | color  | type       |
|============================================================|
| 130    | 1968 | Ford      | Fairlane | Blue   | Roadster   |
| 100    | 2014 | Ford      | Taurus   | Silver | Sedan      |
| 60     | 2015 | Chevrolet | Corvette | Red    | Sports Car |
+============================================================+
SELECT SUM(
  IF(cars.year = "1968", 30, 0) +
  IF(cars.make = "Ford", 100, 0) +
  IF(cars.model = "Mustang", 85, 0) +
  IF(cars.color = "Red", 10, 0) +
  IF(types.name = "Sports Car", 50, 0)
) AS `weight`, cars.*, types.* FROM cars 
LEFT JOIN cars_types ON cars_types.car_id = cars.id
LEFT JOIN types ON cars_types.type_id = types.id
  WHERE year = "1968" 
  OR cars.make = "Ford"
  OR cars.model = "Mustang"
  OR cars.color = "Red"
  OR types.name = "Sports Car"
GROUP BY cars.id
ORDER BY `weight` DESC;

Exact query in mysql.connector and regular MySQL not returning same results


Tag : python , By : Raghaw
Date : March 29 2020, 07:55 AM
With these it helps I want to load the following file from my local server into a database on a remote server: , I resolved this issue, using sqlalchemy and pandas:
import mysql.connector
from mysql.connector.constants import ClientFlag
from sqlalchemy import create_engine
import pandas as pd

DATABASE = 'DB'
USER = 'USER'
PASSWORD = 'PASS'
HOST = 'HOST'
TABLE='TB'
LOCALHOST_USER='USER'

def setup_connection():
    conn = mysql.connector.connect(
        database=DATABASE,
        user=USER,
        password=PASSWORD,
        host=HOST,
        port=3306,
        allow_local_infile=1,
        autocommit=True,
        client_flags=[ClientFlag.LOCAL_FILES]
    )
    cursor = conn.cursor(dictionary=True)
    return conn, cursor

conn, cursor = setup_connection()

connection_string = f'mysql+mysqlconnector://{USER}:{PASSWORD}@{HOST}/{DATABASE}'
mysql_engine = create_engine(connection_string)

cursor.execute(
    f"""
        drop table if exists {DATABASE}.{TABLE};

        create table {DATABASE}.{TABLE} (
            a int,
            b int,
            c int
        );
    """
)

df = pd.read_csv(f'/Users/{LOCALHOST_USER}/Documents/tmp/test.csv')
df.to_sql(con=mysql_engine, name=TABLE, schema=DATABASE, if_exists='replace', index=False)

cursor.close()
conn.close()
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