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Tag: mysql

Python Mysql Queary not returning results

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)

What is a runtime complexity of this sql query?

I would like to know how fast is SELECT * FROM user_table WHERE email = ‘’ 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” column, then the search could be performed in O(1).

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 after import: Data truncated for column… my_date sets to 0000-00-00, even with

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 from the

How to return rows containing decimals in a range

I have the following table: Rows Decimals First Second Third Fourth 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 the second row. How can I specify my query

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, you need to surround the identifier with backticks.

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 2 3 4 5 wp_learndash_user_activity (lua)