problem:
If a record exists, is not inserted, if there is no insert
In SQL SERVER:
create table b(id int)
insert into b select 1
union all
select 2
union all
select 3
union all
select 4
if not exists(select id from b where id=5)
insert into b(id) values(5)
===
MYSQL is not a simple sentence can only be achieved with stored procedures
MYSQL:
create table b(id int);
insert into b(id) values(1),(2),(3),(4);
insert into b(id) values(1),(2),(3),(4);
DELIMITER $$
DROP PROCEDURE IF EXISTS `test`.`sp_b`$$
CREATE PROCEDURE `test`.`sp_b`(in i_id int)
BEGIN
declare cnt int;
select count(1) from b where id=i_id into cnt;
if cnt = 0 then
insert into b select i_id;
end if;
END$$
select count(1) from b where id=i_id into cnt;
if cnt = 0 then
insert into b select i_id;
end if;
END$$
DELIMITER ;
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Reproduced in: https: //my.oschina.net/u/585111/blog/219444