测试PostgreSQL函数

Question

我正在将现有的Sybase系统移动到PostgreSQL，并且在测试我的功能时遇到了麻烦。例如，我有以下代码

drop function if exists contract_line_ins(bigint, bigint, char(10), date, date, numeric(18, 0), numeric(18, 0), integer, bigint); 

create function contract_line_ins (
  in    _contract_id       bigint,
  in    _product_id        bigint,
  in    _number            char(10),
  in    _start_date        date,
  in    _end_date          date,
  in    _history_access    numeric(18, 0),
  in    _subscription_type numeric(18, 0),
  inout _rows_updated      integer,
  inout _id                bigint
)
as $$
declare
  _locus int = 1;    -- Set this in code to indicate current executing statement in exception
  _at text;          -- Used in exception handling

begin
  insert into contract_line(contract_id, product_id, number, start_date, end_date, history_access, subscription_type)
  values (_contract_id, _product_id, _number, _start_date, _end_date, _history_access, _subscription_type)
  returning _id;

  get diagnostics _rows_updated = row_count;

-- Exception handling
  exception when others then
    get stacked diagnostics _at = PG_EXCEPTION_CONTEXT;
    raise notice E'EXCEPTION\nError:   %\nMessage: %\nLocus:   %\nAt:      %', SQLSTATE, SQLERRM, _locus, _at;
end;
$$ language plpgsql;

我很欣赏在这种情况下两个返回值都是多余的，但我被要求不要更改参数，除非绝对必要。

我写了以下测试代码

do language plpgsql $$
declare
  contract_id       bigint = 1;
  product_id        bigint = 2;
  number            char(10) = 'CONTRACT';
  start_date        date = '20160101';
  end_date          date = '20161231';
  history_access    numeric(18, 0) = 3;
  subscription_type numeric(18, 0) = 4;
  rows_updated      int;
  id                bigint;
begin
  perform contract_line_ins(contract_id, product_id, number, start_date, end_date, history_access, subscription_type, rows_updated, id);

  raise notice E'row count % id %', rows_updated, id;
end
$$

当我执行此测试时，我得到以下内容：

[2016-06-18 05:55:17] EXCEPTION
Error:   42601
Message: query has no destination for result data
Locus:   1
At:      PL/pgSQL function contract_line_ins(bigint,bigint,character,date,date,numeric,numeric,integer,bigint) line 7 at SQL statement
SQL statement "SELECT contract_line_ins(contract_id, product_id, number, start_date, end_date, history_access, subscription_type, rows_updated, id)"
PL/pgSQL function inline_code_block line 13 at PERFORM
[2016-06-18 05:55:17] row count <NULL> id <NULL>
[2016-06-18 05:55:17] completed in 43ms

我不明白的是：

1. 为什么“查询没有结果数据的目标”消息？我以为PERFORM是为了防止这种情况
2. 异常发生在我的测试代码中，但正在函数中引发。我原本以为该函数只会报告在自己的体内发生的异常。为什么会这样？

虽然我发现PostgreSQL文档非常好，但我无法找到如何正确执行此操作。

任何建议都感激不尽。

Answer 1

Q1

我认为这是returning _id位给出了一个例外。因为INSERT ... RETURNING应该以列表结尾，而不是变量名。如果要插入行列id值到_id变量 - 将其更改为returning id INTO _id。

Q2

我相信错误发生在函数中