MySQL - Concatenate Two Tables

MYSQL - Concatenate two tables

select * from table_a where actid = 17
union all
select * from table_b where actid = 17

You may (or may not) need to do something about the ids not being unique, such as

select 'Student', table_a.* from table_a where actid = 17
union all
select 'Faculty', table_b.* from table_b where actid = 17

How to join two tables of mysql and concatenate multiple rows into single cell?

Group concat is the easiest way to achieve the output you require.

Concatenate two tables in MySQL

JOIN the two tables:

SELECT
  t1.ID,
  t1.Name,
  t1.Age,
  t2.Occupation,
  t2.Address
FROM table1 t1
INNER JOIN table2 t2 ON t1.ID = t2.ID;

SQL Fiddle Demo

This will give you:

| ID |  NAME | AGE | OCCUPATION |     ADDRESS |
-----------------------------------------------
|  0 |  John |  15 | Bus Driver |        None |
|  1 | Chris |  20 |     Lawyer | some adress |

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If you want to create a new table table3 directly from this select, do this:

CREATE Table Table3
AS 
SELECT
  t1.Name,
  t1.Age,
  t2.Occupation,
  t2.Address
FROM table1 t1
INNER JOIN table2 t2 ON t1.ID = t2.ID;

Like this

How to simply concatenate multiple tables horizontally in MySQL?

    SELECT 
            a.ID1, b.ID2, a.x, b.x, c.x, < and so on >
    FROM 
            a JOIN b ON a.ID1=b.ID1 AND a.ID2=b.ID2
              JOIN c ON a.ID1=c.ID1 AND a.ID2=c.ID2

MySQL merge two tables and get sum

So, instead of JOIN what you need is UNION. You can use "UNION ALL" or "UNION", it depends if you want the duplicated rows or not.

In any case, after the UNION, group that result into a subquery to get the SUM()

SELECT
u.name,
u.code,
SUM(u.num),
FROM
(
SELECT name, code, num FROM tableA
UNION ALL
SELECT name, code, num FROM tableB
) u
GROUP BY u.name, u.code

MySQL join two tables based on a condition

The conditions should be moved to the ON clause.

In MySql a CASE expression can be used to return the result of Boolean expressions (as 1 or 0 for true or false) like this:

SELECT u.name, s.swp_to, s.first_swp 
FROM swipes s LEFT JOIN users u
ON CASE (s.swp_from = :me AND ((s.first_swp NOT IN ('like', 'superlike')) OR (s.first_swp IN ('like', 'superlike') AND s.second_swp NOT IN ('like', 'superlike'))))
  WHEN 1 THEN u.id = s.swp_to
  WHEN 0 THEN u.id = s.swp_from AND (s.swp_to = :me AND s.second_swp <> 'pending')
END; 

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