MYSQL 从 Table1 获取 id 并在插入值时插入到 Table2（用户表单）

Question

I have 2 tables:

Table1

u_id    email
1       user1@y.com
2       user2@h.com

and Table2

id u_id values

had to insert values to table2 with u_id when user enters from form Example:I need to add the value table1 u_id while that user is logged in into table2 that is id increments in table and u_id from table1 and values as user enters from table2

i tried something this query however not successful

insert into table2 (u_id,values)
            values ((select u_id from table1), 'values')

Answer 1

The problem with your query is that the subquery returns multiple rows (one value per row in table1 ), while the database expects a scalar value.

I would expect that you know the email of the current user, and want to recover the corresponding u_id to insert a new row in table2 , along with a literal value. If so, I would recommend the insert... select syntax:

insert into table2 (u_id, val)
select u_id, 'foo' from table1 where email = 'user1@y.com'

Side note: values is a SQL keyword, hence not a good choice for a column name (you would need to quote this identifier every time you use it). I renamed this column to val in the query.