How to use table query statements in ThinkPHP

1. Query a single field

To query a certain field in the table, we can specify the table to query through the table() function, and The find() function means to query only one result, 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

To obtain the complete record in the table, you can use the find() or select() method. 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 Separate fields with commas.

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

Use the select() function to query multiple records in the table that meet the query conditions. The difference from the find() function is that 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 Indicates 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 start of the record Position, 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.

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