I have a DB and when I query a table I get 67 results. The SQL is: I try to connect to the DB, and I get no connection errors. It prints out -1 for rowcount. The connection to the DB appears to be working, the SQL is a simple query… Answer Try adding cursor.fetchall() before the print(cursor.rowcount)
Tag: mysql
Update multiple rows from one SQL UPDATE INNER JOIN with different values
The scenario is a set of tables that contain data related to markets and goods produced at those markets. In the basic example below, you have Ice and this produces water. I have a SQL query which works well and is performant (5ms~). It calculates the stock of Ice required to produce X amount of Water (they a…
What is a runtime complexity of this sql query?
I would like to know how fast is SELECT * FROM user_table WHERE email = ‘test@gmail.com’ is this O(1) or O(n)? how does sql search for a particular row? Answer If there is no index on “email” column, the search complexity is O(N). If there was hash-based index on an “email”…
How can i change SQL date format to: 12th Jun 2021. (as example)
So, I’m trying to insert data from .csv file, but because of the date format I’m using – import causes it to set to 00-00-0000 import settings: format – CSV using load data (otherwise it causing errors and failing to import) Specific format options: none Errors I’m receiving afte…
MySQL – Show the restaurant name and items where price is over a certain value
I have two tables: I am trying to get the restaurnat name, item name and price where all the restaurants’ items have a price higher than 10. Examaple result: restaurant item price The King Fry item 1 12.30 THe King Fry item 2 13.00 The King Fry item 3 10.60 All the items listed on their menu are > 10
How do I get column names of two tables at a time
How do I get the column name of two tables in a single query ? This works for single table. But if I try This throws error. Answer Different queries will be put together using UNION ALL (or UNION only if it’s necessary to exclude identic values which appear in both queries): Since you want to get data f…
How to return rows containing decimals in a range
I have the following table: Rows Decimals First 1.1.1.3.2 Second 16.1.1.1.89.1 Third 3.1.1.1.177.2 Fourth 1.1.1.1.178.3 I only want to return the rows where the second to last decimal is between 0.7 to 0.94 (inclusive), but all the other numbers can contain any value. For the above table, this would be only t…
Fatal error: Uncaught mysqli_sql_exception: Unknown database ‘test_db’. I keep getting this error even though I programatically created the database
Here is the code I am not sure what is going on as I am sure i made no errors while typing. As it keeps showing me that there is an unknown database despite the fact i made a CREATE DATABASE statement. I do not know if there is something else i need to do but by all measures the
funny characters in Sql String
I have a query string that works fine if tableStr is for example MSFT. However, if tableStr is BRK-B, the query fails. How do I get around this? Answer Per MySQL Documentation, “The identifier quote character is the backtick (`)”. This means that if your table name has special characters in it, yo…
MySQL to fill in the blanks with NULLs when their isn’t a row based on set number of IDs from the join
Looking to fill in the blanks with NULLs when there isn’t a record that is for a row that I am expecting. Consider the following wp_posts (p) ID post_title 1 Week 1 2 Week 2 3 Week 3 4 Week 4 5 Week 5 wp_users (u) ID user_email 1 email1@example.com 2 email2@example.com 3 email3@example.com 4 email4@exam…