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Become a Master of Java Streams, Part 2: Intermediate Operations

Want to become a Java Streams Master?

Just like a magic wand, an Intermediate operation transforms a Stream into another Stream. These operations can be combined in endless ways to perform anything from simple to highly complex tasks in a readable and efficient manner.

This article is the second out of five, complemented by a GitHub repository, containing instructions and exercises to each unit.

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How to return parameters from different table rows

I have three tables(table, table2,table3). From table1 i want to return three rows: Title, Desc,time,'products' AS type

From table2 i want to return three rows: group_title, group_desc, created,'groups' AS type

From table3 i want to return three rows: name, occupation,birth,'users' AS type

  $sql = "SELECT DISTINCT * 
    FROM
        (SELECT table1.title, table1.desc, table1.time,'products' AS type
        FROM table1 ORDER BY rand() LIMIT 5) AS T
     UNION ALL
        (SELECT table2.group_name,table2.group_desc,table2.created,'groups' AS type
        FROM tabl2 
        JOIN table1 ON table2.id = table1.id 
         ORDER BY rand() LIMIT 5)
    UNION ALL
        (SELECT table3.name,table3.occupation,table3.birth,'users' AS type
        FROM table3
        JOIN  table1 ON table3.id = table1.id
        ORDER BY rand() LIMIT 5)";

am using Ionic to push those three parameters of an Array to the next page so if i use AS and put the same name. I set a parameter AS type that i need so i can work different types. it has to be 'products' AS type for table1, 'groups' AS type for table2, users as type for table3 i want to separate the objects from each table.

It cant use AS the for the rest of the columns because i want to push the original columns
e.g.

 (SELECT table1.title AS title, table1.desc AS desc, table1.time AS time
    FROM table1 ORDER BY rand() LIMIT 5) AS T
 UNION ALL
    (SELECT table2.group_name AS title,table2.group_desc AS desc,table2.created AS time.....

If i do that it displays the object parameters ok e.g. {{item.title}}

but i can not push or navctrl the parameter as title it has to be group_name. I hope i made myself clear.

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UNION SQL call original rows

Hello i want to UNION three tables from the same database. 

SELECT DISTINCT * 
        FROM
    (SELECT uid as id, name as name, username as username,bio as aboutme, '' as text, 'user' as type, profile_pic as profile_pic, '' as media_pic, '' as group_pic, 'U' as mediatype, '' as image_path FROM users ORDER BY rand() LIMIT 5) AS T

            UNION ALL
            (SELECT group_id as id, group_name as name,'' as username, group_desc as aboutme, '' as text, 'group' as type, '' as profile_pic, '' as media_pic, group_pic as group_pic, 'G' as mediatype, '' as image_path FROM groups ORDER BY rand() LIMIT 5)
        UNION ALL
            (SELECT M.msg_id as id, M.title as name, '' as username,M.description as aboutme, M.message as text, 'media' as type, '' as profile_pic,  M.media_pic as media_pic, '' as group_pic, M.type as mediatype, P.image_path as image_path FROM messages M, user_uploads P ORDER BY rand() LIMIT 5)

It works but i want to return the original names of the rows for example not id but uid or msg_id or group_id separately. But i still need to UNION Thanks in advance