4 recommended articles about the maximum value of a field

MySQL - GROUP BY grouping to get the maximum field value sample code details: Suppose there is a business scenario where user login record information needs to be queried. The table structure is as follows: CREATE TABLE `tb` ( `id` int(11) NOT NULL AUTO_INCREMENT, `uid` int(11) NOT NULL, `ip` varchar(16) NOT NULL, `login_time` datetime, PRIMARY KEY (`id`), KEY (`uid`) ); Let’s get some more test data:

1. MySQL—GROUP BY grouping to get the maximum value of the field sample code details

Introduction: Suppose there is a business scenario where user login record information needs to be queried. The table structure is as follows: CREATE TABLE `tb` (`id` int(11) NOT NULL AUTO_INCREMENT, `uid` int(11) NOT NULL, `ip` varchar(16) NOT NULL, `login_time` datetime, PRIMARY KEY (`id`), KEY

2. Query the maximum value of a certain field, and then assign it to a variable. How to solve it

Introduction: Query the maximum value of a certain field, and then assign it to a variable. I read it online There are a lot of codes, but it doesn't work when inserted into my file. Please help me find out how to query the maximum value of a field and assign it to a variable. I will add 1 to the calculation after querying it.

3. Query the maximum value of a field and then assign it to a variable. How to solve this problem?

Introduction: Query the maximum value of a certain field, and then assign it to a variable. I have seen a lot of codes on the Internet, but they cannot be inserted into my file. Please help me. Let's see how to query the maximum value of a certain field and assign it to a variable. I will add 1 to the calculation after querying it.

4. Use HBase EndPoint (coprocessor) for calculation

Introduction: If you want to collect some statistics on the data in hbase, such as counting the maximum value of a certain field, counting the number of records that meet certain conditions, counting various record characteristics, and classifying them according to the record characteristics ( Similar to sql's group by) ~ The conventional approach is to scan the data of the entire table in hbase, or to be a little more environmentally friendly, add a filter and do some preliminary

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