Question

I’m new! New here, new with MySQL and PHP. And I’m trying to do a little something which has got me all baffled up. Please try and help me guys.

I have a table with some sample data as follows:

ID  NAME    ATTRIBUTE
1   John     123
2   Sean     654
3   John     987
4   Audrey   458
5   John     123
6   Audrey   589
7   Peter    257
8   Marc     125
9   Audrey   326
10  Stan     456
11  Carol    698

And here’s a list of what I intend to do –

1. Select the first 6 records

2. Find Unique Names from the 6 selected records – Expected Result : 3 Unique Names (John, Sean & Audrey)

3. Find the Number of Attributes for each Unique Name from the Selected 6 records – Expected Result: John (3 attributes) , Sean (1 attribute) and Audrey (2 attributes).

4. Count the Number of identical attributes for each of the Unique name from the selected 6 records – Expected Result: Name=> John, Attribute=> 123, No. of Occurrence=> 2, Name=> John, Attribute=> 987, No. of Occurrence=> 1 etc.

5. From the above selections, insert data to a new database table (e.g. Unique Names) in the format:

   a. NameID (Not the same one as the last table, new id – auto generated),
   b. Name

   And in another table (e.g. Attributes)

   a. ID(Auto Generated),
   b. Attribute,
   c. NameID (should be the same as ID in the last) – this is for the relationship between the Unique Names and Attributes table)
   d. Occurrence (of each attribute for each unique name)

6. Once the new tables are filled with the data, I would like to Delete the top 6 selected record from the first table from where they are collected. (The Top Table)

Can someone help me with the MySQL queries and supporting PHP codes for this one. Also, I would like to know the best and fastest possible way to query the MySQL for the above if I have millions of data in the tables.

Answer 1

Question 1:

SELECT t.id,  t.name,t.attribute FROM t LIMIT 6

Question 2:

SELECT DISTINCT t.name FROM (SELECT t.id, t.name, t.attribute FROM t LIMIT 6) t

Question 3:

SELECT t.name, COUNT(t.attribute) AS number_of_attributes FROM(SELECT t.id, t.name, t.attribute FROM t LIMIT 6) t
GROUP BY t.name
ORDER BY number_of_attributes desc

Question 4:

SELECT t.name, t.attribute, COUNT(t.attribute) AS Appears FROM (SELECT t.id, t.name, t.attribute FROM t LIMIT 6) t
GROUP BY t.name,t.attribute
ORDER BY Appears desc

Question 5:
First part: Must be done in 2 steps, first select the unique names-from the top 6 first selected-, then add the auto_increment column:

CREATE TABLE unique_names SELECT DISTINCT t.name FROM t

ALTER TABLE unique_names ADD name_id INT AUTO_INCREMENT PRIMARY KEY FIRST

Second part: the same as the first one, but in this case to get the id we join with the table created in the first part of this step, and then we add the auto_increment column

CREATE TABLE attributes SELECT t.attribute,un.name_id FROM t INNER JOIN unique_names un ON t.name=un.name

ALTER TABLE attributes ADD id INT AUTO_INCREMENT PRIMARY KEY FIRST

Question 6:

DELETE FROM t LIMIT 6

In this case I used t as the original table name