Which ever works for you, but if you can afford to add an column then it would largely simplify your query if not you can always use Query 4 or Query 5. So basically we have an option of adding a column that returns the latest record, for each group last row(or first depend on your query) added a flag last= 1, and make all other rows’ flag last= 0. Let’s discuss what structural changes we could have done to improve the performance. So, let me clear one misconception that MAX(id), is a function that returns the maximum of the rows in that column, Using MAX(id) does not return maximum id of rows in the query result. As we now know the most recent date for each group of records, we can join this data with our original table so that we can get the most recent record for each. And unlike in our example if you do not have different data in columns other than id, it is difficult to catch this problem. A join is a method of linking data between one or more tables based on values of the common column between the tables. You can clearly see the MAX(id) is 8 and id is returning 5, so the result is wrong. You can catch the problem if you run the 2nd query with id in column. Most developers just use query 1 thinking, MAX(id) will give them the row with id = MAX(id) which is wrong. SELECT max(id),id,user_id,first_name,last_name FROM user_log group by user_id DESC SELECT max(id),user_id,first_name,last_name FROM user_log group by user_id DESC Common mistake in using MAX:Ī simple mistake Developers make in this type of queries is using MAX function to get the last records from each group. The performance of this queries can very from data sets to data sets, here the data set taken is symmetrical (each user wise 4 rows), if data is asymmetrical these result will slightly differ, but it is beyond doubt that Query 4 and Query 5 will outperform every other query.
In our example, the most recent row always has the highest id value.
Mysql join latest record how to#
we will give you demo,Source Code and examples for implement Step By Step Good Luck!. In this tutorial, we aim at exploring how to select the most recent record in MySQL. Joining the First Row is an oft-used technique and a vital tool in the analysts. In this post we will show you Best way to implement Left join with last record of right table in Laravel, hear for Find the last record based on a attribute of a table in Laravel with Download. Lets get started by creating a table followed by inserting data into it to be used in the example. In this Post We Will Explain About is Laravel Left join get last record of right table in MYSQL With Example and Demo.Welcome on – Examples, The best For Learn web development Tutorials,Demo with Example! Hi Dear Friends here u can know to How to select last row for each group in Laravel Example Retrieving the last record in each groupSolved MySQL. php – Laravel leftJoin only last record of right table.Left join with last record of right table in Laravel & Mysql.Laravel Left join get last record of right table in MYSQL.
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