The easiest way to generate random records in Mysql is to use the
ORDER BY RAND().
SELECT col1 FROM tbl ORDER BY RAND() LIMIT 1;
This can work fine for small tables. However, for big table, it will have a serious performance problem as in order to generate the list of random rows, because Mysql need to assign random number to each row and then sort them.
Even if you only want random 1 records from 200k+ rows, Mysql need to sort all the records and then extract it.
Posted by
chevrons in
MySQL
Because I found that record save inside the database have typo problem.
How to solve it? Normally I will use PHP str_replace to solve the issue. But now requires use SQL to print out all the record and replace the typo.
Posted by
chevrons in
MySQL
Mysql
regexp or
rlike function it same as PHP preg_match() function.
It save the time write code and filter the data.
Posted by
chevrons in
MySQL
Using Mysql function add asterisk (*) in front of the string.
Example Output:
********MyTestString
*******MyTestString2
**********TestString
Posted by
chevrons in
MySQL
Find the string position. I think most of the Software Engineer will use server side script to do it. I also is the one. For PHP, I will use
strpos to get the position.
Posted by
chevrons in
MySQL
Generally, we stores various values of choices in 1 column of database. For example, we store user’s preferred categories in user table’s. value stored in this field will be like this 1,2,12,22,4
Posted by
chevrons in
MySQL