MariaDB: Insert records (list of tuples) into table if not exists

Question

Currently I have several sql queries that look like this:

INSERT INTO `test` (col1, col2)
SELECT * FROM (SELECT '1','2') AS tmp
WHERE NOT EXISTS (
    SELECT * FROM `test`
    WHERE col1='1' AND col2='2'
) LIMIT 1;


INSERT INTO `test` (col1, col2)
SELECT * FROM (SELECT '3','4') AS tmp
WHERE NOT EXISTS (
    SELECT * FROM `test`
    WHERE col1='3' AND col2='4'
) LIMIT 1;

Generally speaking, as rule of thumb the less queries the better which is why I want to rewrite the sql queries into one query. This should make it even faster when having millions of datasets as the WHERE clause would only iterate through the table once, hence this should be possible:

WHERE col1 in ('1','3') AND col2 in ('2','4')

But when I try multiple select statements in a single query like:

SELECT * FROM 
(SELECT '1','2') AS tmp1,
(SELECT '3','4') AS tmp2

SQL throws this error:

#1136 - Column count doesn't match value count at row 1

The problem is with SELECT * FROM (SELECT '1','2') AS tmp.

How can I use several tuples (1, 2) (3, 4) in the subquery for it meet the WHERE condition?

Is there a shorter and faster way to achieve this?

Any feedback is highly appreciated!

Please ignore the data types; the numbers should be formatted as int not as varchar.

---

UPDATE

When executing the following:

INSERT INTO `test` (col1, col2)
SELECT * FROM
((SELECT * FROM (SELECT '7','8') AS tmp
WHERE NOT EXISTS (
    SELECT * FROM `test`
    WHERE col1='7' AND col2='8'
) LIMIT 1)
UNION
(SELECT * FROM (SELECT '9','9') AS tmp
WHERE NOT EXISTS (
    SELECT * FROM `test`
    WHERE col1='9' AND col2='9'
) LIMIT 1)) t1;

SQL throws: Duplicate column name '9'

Answer 1

You can use UNION ALL to build as many rows as you need:

INSERT INTO test
SELECT
  i.col1
 ,i.col2
FROM
  (
    SELECT 
      1 AS col1
     ,2 AS col2
    
      UNION ALL
      
    SELECT 
      3
     ,4
  )  i
WHERE
  NOT EXISTS
    (
      SELECT
        1
      FROM
        test
      WHERE
        col1 = i.col1
          AND col2 = i.col2
    )

See fiddle here.

After 10.3.3 MariaDB (sort of) supports table-valued constructors, you won't have the ability to name the columns like you would otherwise:

INSERT INTO test
SELECT
  i.`1`
 ,i.`2`
FROM
  (
    VALUES
      (1,2)
     ,(3,4)
  )  i
WHERE
  NOT EXISTS
    (
      SELECT
        1
      FROM
        test
      WHERE
        col1 = i.`1`
          AND col2 = i.`2`
    )

Answer 2

Your SELECT with two select can be JOINed or UNIONìted

As you want to insert two rows, you need UNION like this

INSERT INTO `test` (col1, col2)
SELECT * FROM
((SELECT * FROM (SELECT '1','2') AS tmp
WHERE NOT EXISTS (
    SELECT * FROM `test`
    WHERE col1='1' AND col2='2'
) LIMIT 1)
UNION
(SELECT * FROM (SELECT '3','4') AS tmp
WHERE NOT EXISTS (
    SELECT * FROM `test`
    WHERE col1='3' AND col2='4'
) LIMIT 1)) t1;

I don't see why it should give you an error

INSERT INTO `test` (col1, col2)
SELECT * FROM
((SELECT * FROM (SELECT '1','2') AS tmp
WHERE NOT EXISTS (
    SELECT * FROM `test`
    WHERE col1='1' AND col2='2'
) LIMIT 1)
UNION
(SELECT * FROM (SELECT '3','4') AS tmp
WHERE NOT EXISTS (
    SELECT * FROM `test`
    WHERE col1='3' AND col2='4'
) LIMIT 1) 
UNION
(SELECT * FROM (SELECT '9','9') AS tmp  WHERE col1='9' AND col2='9')
) t1;