mysql连接表php从2个表中检索数据

Question

was wondering if joining tables is the best way to retrieve data from multiple columns like i want to retrieve the fields from two columns in a table and one column from another table. I was wondering if this is the best way to do this.

and for retrieving the query from php i should just do a mysql_num_rows loop. correct?

Answer 1

Yes, a join is absolutely better than most alternatives; it's why joins exist. Your schema must support this with appropriate identification columns which are shared by both tables (ie employees.id == paychecks.employee_id) . You may need to create an index if you find the default indexes are not being used correctly (check the execution plan https://dev.mysql.com/doc/refman/5.7/en/index-hints.html )

The way you iterate results in PHP depends on the library you use to fetch the data from MySQL and what you need to do with the data.