Introduction to statistical query methods in thinkphp

In ThinkPHP, the system provides the following query methods to facilitate the use of statistics in the later stage:

count() represents the total number of queries in the query table Number of records

max() means querying the maximum value of a certain field

min() means querying the minimum value of a certain field

avg( ) means querying the average value of a certain field

sum() means finding the sum of a certain field

1. count method

Syntax:

$model -> [where() -> ] count();

Case: Query the total number of records in the department table.

    //count方法
    public function test(){
        //实例化模型
        $model = M('Dept');
        //count方法
        $result = $model -> count();
        //打印
        dump($result);
 
    }

Display results:

The return value is in the form of characters.

Results in sql tracking information:

Information in database:

2. max method

Syntax:

$model -> max('字段名');

Case: Query the department with the largest id in the department table.

In future development, there will be an application that queries the id of the last registered member through the max method.

    //max方法
    public function test(){
        //实例化模型
        $model = M('Dept');
        //max方法
        $result = $model -> max('id');
        //打印
        dump($result);
    }

Display results:

The return value is in the form of characters.

Results in sql tracking information:

Information in database:

$model -> min('字段名')

    //min方法
    public function test(){
        //实例化模型
        $model = M('Dept');
        //max方法
        $result = $model -> min('id');
        //打印
        dump($result);
    }

$model -> avg('字段名');

    //avg方法
    public function test(){
        //实例化模型
        $model = M('Dept');
        //max方法
        $result = $model -> avg('id');
        //打印
        dump($result);
    }

##5. sum method

Syntax:

$model -> sum('字段名');

Case: Query the sum of field ids.

    //sum方法
    public function test(){
        //实例化模型
        $model = M('Dept');
        //max方法
        $result = $model -> sum('id');
        //打印
        dump($result);
    }

Display results:

The return value is also in the form of characters.

Results in sql tracking information:

Information in the database:

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