MySQL，使用其他表中的数据创建表

Question

Could you help me with designing a MySQL query for creating a table with data from other 3 tables?

Database design:

What I have tried was:

INSERT INTO SklepZaloha (TIME)
    SELECT TIME FROM Item1;
INSERT INTO SklepZaloha (Boiler)
    SELECT Value FROM Item1;
INSERT INTO SklepZaloha (Zpatecka)
    SELECT Value FROM Item2;
INSERT INTO SklepZaloha (Vymnenik)
    SELECT Value FROM Item3;

But that results in: aaabbbccc instead of: abcabcabc

Answer 1

Your INSERT ... SELECT needs to insert the entire row at once, not nibble away one value at a time. To do this, you need to use a JOIN .

INSERT INTO SklepZaloha
    (`Time`, Boiler, Zpatecka, Vymnenik)
  SELECT i1.`Time`, i1.Value, i2.Value, i3.Value
    FROM Item1 i1
    INNER JOIN Item2 i2
      ON i1.`Time` = i2.`Time`
    INNER JOIN Item3 i3
      ON i1.`Time` = i3.`Time`;

The SELECT portion would also be the correct syntax for a SELECT ... INTO OUTFILE query.

Answer 2

I can tell you one thing, you're going to have to use a prepared statement in a stored procedure in all likelihood. It's been some time since I've done this, but within a stored procedure you can access the tables with the data and then construct a prepared statement that you then execute.

The MySQL documentation on stored procedures as well as prepared statements is pretty good.

I do vaguely remember, however, there being an issue with executing statements of this type in a stored procedure.

Sorry I can't be more helpful.

Michael