H2 SQL database - INSERT if the record does not exist

Question

I would like initialize a H2 database, but I am not sure if the records exist. If they exist I don\'t want to do anything, but if they don\'t exist I would like to write the

Answer 1

To do this you can use MySQL Compatibility Mode in H2 database. Starting from 1.4.197 version it supports the following syntax: INSERT IGNORE INTO table_name VALUES ...

From this pull request:

INSERT IGNORE is not supported in Regular mode, you have to enable MySQL compatibility mode explicitly by appending ;MODE=MySQL to your database URL or by executing SET MODE MySQL statement.

From official site:

INSERT IGNORE is partially supported and may be used to skip rows with duplicate keys if ON DUPLICATE KEY UPDATE is not specified.

Answer 2

Here is another way:

CREATE TABLE target (C1 VARCHAR(255), C2 VARCHAR(255));

MERGE INTO target AS T USING (SELECT 'foo' C1, 'bar') AS S ON T.C1=S.C1
WHEN NOT MATCHED THEN
    INSERT VALUES('foo', 'bar')

When a row in S matches one or more rows in T, do nothing. But when a row in S is not matched, insert it. See "MERGE USING" for more details:

https://www.h2database.com/html/commands.html#merge_using

Answer 3

The following works for MySQL, PostgreSQL, and the H2 database:

drop table ACCESSLEVELS;

create table ACCESSLEVELS(id int, name varchar(255));

insert into ACCESSLEVELS select * from (
select 0, 'admin' union
select 1, 'SEO' union
select 2, 'sales director' union
select 3, 'manager' union
select 4, 'REP'
) x where not exists(select * from ACCESSLEVELS);

Answer 4

MERGE INTO ACCESSLEVELS 
  KEY(ID) 
VALUES (0, 'admin'),
  (1, 'SEO'),
  (2, 'sales director'),
  (3, 'manager'),
  (4, 'REP');

Updates existing rows, and insert rows that don't exist. If no key column is specified, the primary key columns are used to find the row.