How does thinkphp determine query results?

When using PHP language for data operations, we often need to query the data in the database through SQL statements and then display it to the user through the background page. In this process, we need to judge the query results so that we can handle it accordingly when abnormal situations occur. When developing using the ThinkPHP framework, how to judge the query results? This is described in detail below.

1. Query method

To perform data query under the ThinkPHP framework, we usually use the following methods of the Model class:

1. find() method: Query The first matched data in the data table, and the data is returned in the form of a one-dimensional associative array.
2. select() method: Query all matching data in the data table and return all data in the form of an array.
3. field() method: Query the data of the specified field.
4. where() method: Query data under specific conditions.
5. limit() method: Query the specified number of data items in the data table.
6. order() method: Query the sorting method of the specified field in the data table.
7. join() method: Query related data in multiple data tables.
8. count() method: Query the total number of data under specific conditions in the data table.

etc.

2. Judge the query results

After using the above method to obtain the data in the database, we usually need to judge the query results to determine the legality and correctness of the returned data. The method of judging the query result is as follows:

1. Determine whether the query result is empty

When performing data query on the database, if the query result is empty, it will cause abnormalities in subsequent data operations. Therefore, when developing using the ThinkPHP framework, we usually judge the query results through the following code:

$res = $User->where('id='.$id)->find();
if(empty($res)){
    echo "查询结果为空！";
}

2. Determine whether the query results are consistent with the expected results

When performing data queries , we usually need to verify the query results to determine whether they are consistent with the expected results. The routine operations are as follows:

$res = $User->where('id='.$id)->find();
if($res['name'] !== 'abc'){
    echo "查询结果与预期结果不一致！";
}

3. How to process the query results

After judging the query results, we usually need to perform data operations, such as updating and deleting data, etc. For different data operations, our processing methods are also different. The following are some common processing methods:

1) Delete data:

$res = $User->where('id='.$id)->delete();
if($res){
    echo "删除成功！";
}else{
    echo "删除失败！";
}

2) Update data:

$data = array('name'=>'abc','age'=>20);
$res = $User->where('id='.$id)->save($data);
if($res){
    echo "更新成功！";
}else{
    echo "更新失败！";
}

3) Insert data:

$data = array('name'=>'abc','age'=>20);
$res = $User->add($data);
if($res){
    echo "插入成功！";
}else{
    echo "插入失败！";
}

4) Other operations:

In addition to the above common data operations, we will also encounter some special situations during the actual development process, such as querying multi-table data, data counting, data paging, etc. For these situations, we need to carry out special handling according to the specific circumstances. When the data processing is completed, we need to verify the data again to ensure the correctness and legality of the data operation.

Summary:

When using the ThinkPHP framework for data operations, we need to judge the query results to ensure the correctness and legality of the data. There are many ways to judge query results, and we need to choose according to the specific situation. At the same time, before performing data operations on the query results, we need to further verify the data to ensure the correctness and legality of the operations. This is an important guarantee to ensure program stability.

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