从plpgsql函数返回一个select

Question

我需要从plpgsql函数返回一个动态生成的select语句.这是我到目前为止:

CREATE OR REPLACE FUNCTION qa_scf(cname character varying, tname character varying)
RETURNS text AS
$BODY$
BEGIN
return '* from ' ||tname|| 'where ' ||cname ||' != ''AL''';
end;
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100;

调用者从批处理文件中运行:

select qa_scf('state', 'testtable')

这将返回文字文本"qa_scf*from testtable where state!='AL'".我需要从sql批处理文件运行此查询,但我似乎无法找到正确的return语句让此函数返回一个字符串,然后让sql批处理执行它.我正在使用Postgres 9.0.

Answer 1

返回类型应为SETOF RECORD.执行和返回SQL将变为RETURN QUERY EXECUTE.您的查询缺少SELECT.在那之前还有空白.

CREATE OR REPLACE FUNCTION qa_scf(cname character varying, tname character varying)
RETURNS SETOF RECORD AS
$BODY$
BEGIN
    RETURN QUERY EXECUTE 'SELECT * from ' ||tname|| ' where ' ||cname ||' != ''AL''';
END;
$BODY$
LANGUAGE plpgsql;

调用此函数会变得有点复杂,因为您必须在结果中指定所需的列.像这样:

SELECT *
FROM qa_scf('foo', 'bar') AS t(col1_name col1_type, ...);