Tag Archives: mysql tips & tricks

How to delete duplicate MySQL records with duplicate field value (as ID)

For some reason i had duplicate entries in my WP database. The ID field in wp_users table was tempered with and was changed to Non Auto-Increment to insert records on the will. I deleted all ID=null records manually and then tried to change it to AUTO INCREMENT but it came up with Duplicate Entry error and then i found that it had duplicated/multiple entries with same IDs as well. Here’s the remedy i had to apply in order to delete those duplicate entries and change ID field to AUTO INCREMENT once again. Continue reading

A few notes on joining a MySQL table to itself to get unique combination of field data

Just a few notes on joining a MySQL table to itself to get unique combination of data stored in its fields.

Suppose we have a MySQL table named `keywords` having fields `word1`, `word2` and `word3`. Once we have got a few records inserted into this table we would want to show all possible combination of keywords stored in those fields. For example, a select query returns a following set of data: Continue reading

Calculating difference between two mysql dates in seconds

Here is a quick way to calculate the difference between two mysql dates in number of seconds. In my case, i required to fetch all entries for which the difference between current time stamp and date in a table field would be less than 5 minutes. Continue reading