How to use table query statements in ThinkPHP

ThinkPHP is an excellent PHP open source framework that has been successfully used in many web development projects. It is a lightweight framework, easy to use, and provides rich features. Among them, database operation is an essential part of the development project. Query statements are an important part of database operations. This article will introduce the use of table query statements in ThinkPHP.

1. Query a single field

To query a certain field in the table, we can use the table() function to specify the table to be queried, while the find() function means to query only one field The result is similar to SELECT * FROM table_name WHERE column_name = 'value' LIMIT 1 in MySQL.

Sample code:

$data = Db::table('user')->where('id', 1)->value('username');
echo $data; // 输出结果：'张三'

In the above code, we use the table() function to specify the table to be queried as user, and then use the where() function to specify the query conditions. Here we only query the id The record is 1, and uses the value() function to query the value of the username field.

2. Query the entire record

If you want to query the entire record in the table, we can use the find() function or select() function. Among them, the find() function means to query the first record that meets the conditions, and the select() function means to query all the records that meet the conditions.

Sample code:

$data = Db::table('user')->where('username', '张三')->find();
print_r($data); // 输出结果：['id' => 1, 'username' => '张三', 'age' => 25]

In the above code, we first use the table() function to specify the table to be queried as user, and then use the where() function to specify the query conditions, and query username as 'Zhang Three' records, and finally use the find() function to query the entire record.

3. Query multiple fields

If you want to query multiple fields in the table, we can use the field() function to specify the fields to be queried. Multiple fields are separated by commas. open.

Sample code:

$data = Db::table('user')->where('id', 1)->field('username, age')->find();
print_r($data); // 输出结果：['username' => '张三', 'age' => 25]

In the above code, we use the field() function to specify the fields to be queried as username and age, query the records with id 1, and finally use the find() function to query The entire record.

4. Query multiple records

If you want to query multiple records in the table that meet the query conditions, we can use the select() function. Different from the find() function, the select() function returns a two-dimensional array composed of the result set array.

Sample code:

$data = Db::table('user')->where('age', '>', 20)->select();
print_r($data); // 输出结果：[['id' => 1, 'username' => '张三', 'age' => 25], ['id' => 2, 'username' => '李四', 'age' => 28]]

In the above code, we use the table() function to specify the table to be queried as user, and then use the where() function to specify the query conditions to query records whose age is greater than 20 , and use the select() function to query multiple records.

5. Sorting query

If you want to sort the query results, we can use the order() function, where the parameter can be asc for ascending order, or desc for descending order.

Sample code:

$data = Db::table('user')->where('age', '>', 20)->order('age desc')->select();
print_r($data); // 输出结果：[['id' => 2, 'username' => '李四', 'age' => 28], ['id' => 1, 'username' => '张三', 'age' => 25]]

In the above code, we use the where() function to specify the query conditions, query records with an age greater than 20, and use the order() function to sort the results in descending order by age. Finally, use the select() function to query multiple records.

6. Paging query

If the query result has many records, we can use the limit() function to perform paging query, where the first parameter indicates the starting position of the record, and the second parameter Indicates the number of records queried.

Sample code:

$data = Db::table('user')->where('age', '>', 20)->order('age desc')->limit(0, 1)->select();
print_r($data); // 输出结果：[['id' => 2, 'username' => '李四', 'age' => 28]]

In the above code, we use the where() function to specify the query conditions, query records with an age greater than 20, and use the order() function to sort the results in descending order by age. Then use the limit() function to query the first record.

To sum up, the above is an introduction to the use of table query statements in ThinkPHP. I hope it will be helpful to everyone's learning. In actual development, different queries require different statements, and developers need to choose the most appropriate query method based on specific needs.

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