Recent questions tagged Mysql

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mysql - Why does STRAIGHT_JOIN so drastically improve this query, and what does it mean when it is written after the SELECT keyword?

I have the following MySql query: select t1.* from Table1 t1 inner join Table2 t2 on t1.CommonID = t2. ... The database engine is InnoDB. Thanks See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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700 views

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mysql - Replace Default Null Values Returned From Left Outer Join

I have a Microsoft SQL Server 2008 query that returns data from three tables using a left outer join. Many ... default to zero if possible. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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578 views

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mysql - Implementing the Hacker News ranking algorithm in SQL

Here's how Paul Graham describes the ranking algorithm for Hacker News: News.YC's is just (p - 1) / ... formula-should-be-used-to-determine-hot See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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726 views

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mysql - phpmyadmin "no data received to import" error, how to fix?

I am using XAMPP on a pc atwork to host a database. I exported a backup ("bintra.sql") using phpmybackuppro. I use ... file. I don't know why. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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686 views

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mysql - Count distinct values

I have a data set asking a customer how many pets they have for example. Is there a way with one query I can count ... 2 had 3 Pets 1 had 4 Pets See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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564 views

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mysql - Rolling back a failed Rails migration

How do you roll back a failed rails migration? I would expect that rake db:rollback would undo the failed migration ... a better way than that. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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mysql - Multiple table joins in rails

How do I write the mysql query below into rails activerecord select A.*, B.* from raga_contest_applicants_songs AS A ... use join on 3 tables. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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773 views

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mysql - PHP forums - how to cope with unread discussions / topics / posts

I know this question has been asked here a couple of times, but none of the answers had pleased me. This ... other forum systems cope with it? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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411 views

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mysql - What is difference between storing data in a blob, vs. storing a pointer to a file?

I have a question about the blob data type in MySQL. I read that the data type can be used to store files. I ... to a file on the file system? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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850 views

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mysql - Database design for apps using "hashtags"

database design question here. Say we had a webapp or something that uses hashtags for 20-40 word notes. What is ... the best way to store them? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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440 views

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mysql - Faster way to delete matching rows?

I'm a relative novice when it comes to databases. We are using MySQL and I'm currently trying to ... improve that. Reference: EXPLAIN Statement See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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587 views

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mysql is not recognised as an internal or external command,operable program or batch

I had set the MySQL path, but still getting the same error. Please let me know whether I followed the ... correct path and its settings. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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467 views

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mysql - Move node in nested set

I'd need a MySQL query that moves a node and all its children within a nested set. I found this site, but ... again since it will loose its ID. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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570 views

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mysql - Table with 80 million records and adding an index takes more than 18 hours (or forever)! Now what?

A short recap of what happened. I am working with 71 million records (not much compared to billions of records ... my table given this scenario? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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470 views

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mysql - ERROR: Failed to build gem native extension (mysql2 on rails 3.2.3)

I'm trying to install the mysql2 gem with Rails 3.2.3 and it's failing: ★ bundle install Fetching gem ... sounds like a pretty horrible idea. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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591 views

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mysql - How to reset the primary key of a table?

In my table tbphotos I had a 100 records. I then deleted all the records and now that I want to ... I am using MySQL administrator account. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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820 views

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mysql - Size for storing IPv4, IPv6 addresses as a string

what should be the ideal size for storing IPv4, IPv6 addresses as a string in the MySQL database. should varchar(32) be sufficient? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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662 views

1 answer

mysql - move rows from one table to another

If i have two tables that are identical in structure, how can i move a set of rows from 1 table to the ... but this wouldnt be a deal breaker. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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508 views

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mysql - What's the differences between stored procedures, functions and routines?

In MySQL database context, what is the difference among these 3 terms: stored procedure stored function stored ... are considered as what? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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879 views

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mysql - BOOLEAN or TINYINT confusion

I was designing a database for a site where I need to use a boolean datetype to store only 2 states, true ... 5.5/en/numeric-type-overview.html See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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780 views

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mysql - Why does "_" (underscore) match "-" (hyphen)?

I have to look for a PDF manual using this query: root@localhost:test> select * from a where name like ' ... the name to be taz_manual%.pdf? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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689 views

1 answer

mysql - Why is SQLAlchemy count() much slower than the raw query?

I'm using SQLAlchemy with a MySQL database and I'd like to count the rows in a table (roughly 300k). ... the initial query is slower though. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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568 views

1 answer

mysql - WooCommerce: Finding the products in database

I'm creating a website using WooCommerce and I want to restrict the available products to users depending on the ... ? Thank you in advance. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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933 views

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mysql - Python db-api: fetchone vs fetchmany vs fetchall

I just had a discussion today with some coworkers about python's db-api fetchone vs fetchmany vs fetchall. I'm ... .fetchall(): print id, name See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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430 views

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mysql - Database Design: inventory and sales system?

I need to develop a inventory and sales system. For inventory, I need to be able to keep track of ideal stock ... and how to record the sales. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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623 views

1 answer

mysql - SQL Query Where Field DOES NOT Contain $x

I want to find an SQL query to find rows where field1 does not contain $x. How can I do this? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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558 views

1 answer

mysql - How to count the number of instances of each foreign-key ID in a table?

Here's my simple SQL question... I have two tables: Books ----------------------------- ... other vendor-specific features). Thanks in advance! See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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496 views

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mysql - Best practices to store CreditCard information into DataBase

In my country the online payments are not an old thing, the first time i saw a web application taking payments ... etc. What have you done? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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