Home >PHP Framework >ThinkPHP >How to perform multi-table link query in thinkphp
To learn to perform multi-table link queries in ThinkPHP, you first need to master the basic syntax. In ThinkPHP, you can perform multi-table link queries in the following ways:
Db::table('table1') ->alias('t1') ->join('table2 t2', 't1.id = t2.table1_id') ->join('table3 t3', 't1.id = t3.table1_id') ->where('t1.id', $id) ->select();
In the above statement, we perform multi-table links through the join
method, where the first parameter is the link to be The table name, the second parameter is the link condition. We can use the alias alias
to add an alias to the table to facilitate subsequent operations.
In the where
method, we can specify the conditions that need to be filtered. In this example, we use t1.id
to filter the records whose id
field is equal to $id
in the t1
table.
We may need to perform more complex connection queries to integrate data from multiple tables for statistical analysis. At this time, we can use the aggregate function provided by ThinkPHP to perform calculations.
For example, if we want to count the number of orders for each user, we can use the following statement to query:
Db::table('user') ->alias('u') ->join('order o', 'u.id = o.user_id') ->field('u.*, COUNT(o.id) as order_num') ->group('u.id') ->select();
In the above statement, we used the COUNT
function to count order
The order quantity of each user in the table, and use the group
method to group the results according to u.id
.
In addition, we can also use HAVING
conditions for further filtering. For example, if we want to filter out users whose order quantity is greater than or equal to 5, we can use the following statement:
Db::table('user') ->alias('u') ->join('order o', 'u.id = o.user_id') ->field('u.*, COUNT(o.id) as order_num') ->group('u.id') ->having('order_num >= 5') ->select();
In the above statement, we use the HAVING
condition to filter out users whose order quantity is greater than or equal to 5 User.
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