postgresql - PSQL 脚本中的变量而不创建函数

Question

我试图在下面的示例中使用变量运行 PSQL 脚本，而无需声明函数并且必须调用它们。

DECLARE
    result TEXT;
BEGIN
    SELECT INTO result name 
FROM test;

    RAISE NOTICE result;
END;

其中表test只有 1 行和列。这是否可能无需将此脚本包装在函数中。这将使我可以更轻松地通过命令行调用脚本。

多谢你们。

Answer 1

You can use DO to create and execute an anonymous function:

DO executes an anonymous code block, or in other words a transient anonymous function in a procedural language.

Something like this:

do $$
    declare result text;
    begin
        select name into result from test;
        raise notice '%', result;
    end;
$$;

I also fixed your raise notice.

If you just want to dump the single value from the table to the standard output in a minimal format (i.e. easy to parse), then perhaps --tuples-only will help:

-t
--tuples-only
Turn off printing of column names and result row count footers, etc. This is equivalent to the \t command.

So you could say things like this from the shell:

result=$(echo 'select name from test;' | psql -t ...)