大约有 7,000 项符合查询结果（耗时：0.0239秒） [XML]
MySQL select 10 random rows from 600K rows fast
...imple, to gaps, to non-uniform with gaps.
http://jan.kneschke.de/projects/mysql/order-by-rand/
For most general case, here is how you do it:
SELECT name
FROM random AS r1 JOIN
(SELECT CEIL(RAND() *
(SELECT MAX(id)
FROM random)) AS id)
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How to create relationships in MySQL
... to do what the rest of the class is doing, but with raw SQL commands with MySQL instead of using Access.
8 Answers
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String concatenation in MySQL
I am using MySQL and MySQL Workbench 5.2 CE. When I try to concatenate 2 columns, last_name and first_name , it doesn't work :
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How to find Unused Amazon EC2 Security groups
... from complete. So I decided to write my own script. I used the AWS CLI, MySQL and some “Bash-foo” to perform the following:
Get a list of all EC2 security groups.
I store the group-id, group-name and description in a tabled called “groups” in a MySQL database called aws_security_groups ...
Which ORM should I use for Node.js and MySQL? [closed]
I'm rewriting a project to use Node.js. I'd like to keep using MySQL as the DB (even though I don't mind rewriting the schema).
I'm looking for a simple-to-use, reasonable-performance ORM, which supports caching, many-to-one and many-to-many relations.
From the MySQL ORMs I could find, persistencej...
How to select date from datetime column?
...
You can use MySQL's DATE() function:
WHERE DATE(datetime) = '2009-10-20'
You could also try this:
WHERE datetime LIKE '2009-10-20%'
See this answer for info on the performance implications of using LIKE.
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How to convert an image to base64 encoding?
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Here is the code for upload to encode and save it to the MySQL
if (!isset($_GET["getfile"])) {
if ($_FILES["file"]["error"] > 0) {
echo "Error: " . $_FILES["file"]["error"] . "<br>";
} else {
move_uploaded_file($_FILES["file"]["tmp_name"], $_FILES[...
Get query from java.sql.PreparedStatement [duplicate]
...To my experience, the ones which do so are at least the PostgreSQL 8.x and MySQL 5.x JDBC drivers. For the case your JDBC driver doesn't support it, your best bet is using a statement wrapper which logs all setXxx() methods and finally populates a SQL string on toString() based on the logged informa...
How do I escape reserved words used as column names? MySQL/Create Table
...and one problem is a class may have a field name key which is a reserved MySQL keyword. How do I escape it in a create table statement? (Note: The other problem below is text must be a fixed size to be indexed/unique)
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Is there an SQLite equivalent to MySQL's DESCRIBE [table]?
... SQLite . It would be nice to be able to see the details for a table, like MySQL's DESCRIBE [table] . PRAGMA table_info [table] isn't good enough, as it only has basic information (for example, it doesn't show if a column is a field of some sort or not). Does SQLite have a way to do this?
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