Question

I have 2 tables:

table1
    id someval 
    -----------
    1      23  
    2      56  
    3      76  
    4     456  
    5      53  
    6      67  
    7      12  
    8      43  
    9      99  
    10    567
    11     55
    12      6
    13     55
    14     56
    15      1
    16    444
    17     66 
    18     89
    19      6    


table2
    id someval 
    -----------
    1     23.3 
    2     5.6  
    3     8.76 
    4     4.56 
    5      5.3 
    6      6.7 
    7      1.2 
    8      4.3 
    9      9.9 
    10    56.7
    11     6.7
    12    44.8 

What query would join them and output (id is modified for second table):

table1AND2

    id someval 
    -----------
    1      23  
    2      56  
    3      76  
    4     456  
    5      53  
    6      67  
    7      12  
    8      43  
    9      99  
    10    567
    11     55
    12      6
    13     55
    14     56
    15      1
    16    444
    17     66 
    18     89
    19      6   
    20    23.3 
    21    5.6  
    22    8.76 
    23    4.56 
    24    5.3 
    25    6.7 
    26    1.2 
    27    4.3 
    28    9.9 
    29    56.7
    30    6.7
    31    44.8 

Is there a way to do this in general for any 2 tables of any row size?

Answer 1

Use:

  SELECT a.id,
         a.someval
    FROM TABLE1 a
UNION ALL
  SELECT b.id + (SELECT MAX(id) FROM TABLE1) AS id,
         b.someval
    FROM TABLE2 b
ORDER BY id

UNION removes duplicates; UNION ALL does not remove duplicates, and is faster for it.

To insert into another table:

INSERT INTO another_table
  SELECT a.id,
         a.someval
    FROM TABLE1 a
UNION ALL
  SELECT b.id + (SELECT MAX(id) FROM TABLE1) AS id,
         b.someval
    FROM TABLE2 b
ORDER BY id

…that’s assuming there’s only two columns, id & somecol/etc, in the new table.