Summarize the basic usage and examples of Sum function in thinkphp

During the development process, we often need to perform sum operations on data, such as counting the sum of a certain data field, etc. In ThinkPHP, the Sum function can help us easily implement this operation. This article will introduce the basic usage and examples of Sum function in ThinkPHP.

1. Basic syntax

The basic syntax of the Sum function in ThinkPHP is as follows:

$sum = Db::name('table')->where($where)->sum('field');

Among them, Db::name('table') represents instantiating a data table operation object, $where represents query conditions, 'field' represents the data table fields that need to be summed. After executing the above statement, $sum is the required sum.

2. Example

Suppose we have a user table user, which contains the fields id and score. Now we need to count the total score of users. Then, we can use the following code to achieve it:

$sum = Db::name('user')->sum('score');

In the above code, directly call Db::name('user')->sum('score') to obtain the score The sum of the fields. If you need to filter some data, you can add a where statement, such as:

$sum = Db::name('user')->where('score>60')->sum('score');

The above code means that only the total scores of users with a score greater than 60 will be counted.

In addition to single-table query, the Sum function can also be combined with the join() function to query multiple tables, such as:

$sum = Db::name('user')
       ->alias('u')
       ->join('order o', 'u.id = o.user_id')
       ->where('o.create_time', '>=', '2021-01-01')
       ->sum('o.price');

The above code indicates querying the total amount of orders placed by users since 2021. Among them, the user and order table are associated through the join() function, and the sum operation is performed based on the amount field price of the order table.

It should be noted that if the field type in the database is floating point, the summation result will have errors. You can use the round function to correct it, such as:

$sum = round(Db::name('user')->sum('score'),2);

The above code means retaining 2 decimal places and rounding the sum of the score field.

Summary

Through this article, we learned about the basic syntax and usage examples of the Sum function in ThinkPHP. When you need to perform sum statistics on data during project development, you can easily implement it through the Sum function.

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