Submit multiple queries same time mysql inserting same id twice

Question

Want to submit auto-increment value of table_a into table_b at same time. I first inserting record into table_a and then fetching last primary id from table_a and inserting it into table_b. It works well at slow speed like 20 records per sec, but a fast speed and multi user level it inserting duplicate id of table_a into table_b.

Is my approach is wrong ? Please suggest better way to do this.

code

query1 = "insert into `table_a` (`aid`,`name`) values(null,'val')";

query2 = "select `id` from `table_a` order by `id` desc limit 1";

$aid='retrieved_value';

query3 = "insert into table_b (`bid`,`aid`,`btype`) values (null,'$aid','val')";

Jonathan Hall · Accepted Answer · 2018-01-11 19:25:54Z

2

Yes, your approach is wrong. It is very racy. You have no guarantee that query2 returns the id related to query1. A better approach is to use the last_insert_id function.

answered Jan 11, 2018 at 19:25

Jonathan Hall

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