SQL 如果一行不存在插入，否则不要在 postgres 中插入

If a row does not exists insert else don't insert in postgres

提问by JumpOffBox

I need to check if a row exists or not. If it does not exist, it should be inserted.

我需要检查一行是否存在。如果不存在，则应插入。

This is in postgresand I am trying to insert row through a shell script. When I run the script it does not show error but it does not insert into table even though no matching row is present.

这是在postgres，我正在尝试通过 shell 脚本插入行。当我运行脚本时，它不会显示错误，但即使不存在匹配的行，它也不会插入到表中。

回答by Andres Olarte

I like the solution they mention here

我喜欢他们在这里提到的解决方案

INSERT INTO table (id, field, field2)
       SELECT 3, 'C', 'Z'
       WHERE NOT EXISTS (SELECT 1 FROM table WHERE id=3);