如何在 GNAT CE 2019 中查询 PostgreSQL

Question

我正在尝试使用 GNAT CE 2019 查询 PostgreSQL 数据库。我的数据库中有两个表，car 和 person：

mydb1-# \dt
         List of relations
 Schema |  Name  | Type  |  Owner   
--------+--------+-------+----------
 public | car    | table | postgres
 public | person | table | postgres
(2 rows)

我想执行一个简单的 Select 语句，当我在终端中使用 psql 执行此操作时，返回的内容如下：

mydb1=# SELECT * FROM Person;

              person_uid              | first_name | last_name  | gender |            email             | date_of_birth | country_of_birth |               car_uid                
--------------------------------------+------------+------------+--------+------------------------------+---------------+------------------+--------------------------------------
 75f5e55d-12b2-463e-93ff-1c921e44c3e1 | Audrie     | Vasyukov   | Female | avasyukovd6@domainmarket.com | 1988-11-24    | Guatemala        | 
 9e3f7f90-6e9a-4f2d-ae4e-c852d819ed33 | Nefen      | Philippard | Male   | nphilippardd7@economist.com  | 2006-11-08    | Russia           | 
 ffad6113-2321-47c3-8e1d-b8bbe1f7ffa1 | Leonore    | Garthland  | Female | lgarthlandd8@furl.net        | 1991-03-23    | Canada           | 
 268c1977-a5cc-4794-9cdd-e0e4af7890b9 | Yank       | Turfitt    | Male   | yturfittd9@exblog.jp         | 1990-02-07    | China            | 
 3c815fa3-74b9-493a-9466-f32010806b16 | Benn       | Pawley     | Male   | bpawleyda@indiegogo.com      | 2006-10-28    | Russia           | 
 690fc9e9-309e-4d70-8dab-167653b99763 | Tod        | Easen      | Male   | teasend4@php.net             | 1990-08-24    | China            | 5fa7490e-ba42-4a96-b806-097bbb16e30e

但是，我想在 GNAT CE 2019 中执行此操作。这是我的 main.adb 文件当前的外观：

with GNATCOLL.SQL.Postgres;  use GNATCOLL.SQL.Postgres;
with GNATCOLL.SQL.Exec;      use GNATCOLL.SQL.Exec;
with GNATCOLL.VFS;           use GNATCOLL.VFS;
with GNATCOLL.SQL.Inspect;   use GNATCOLL.SQL.Inspect;
with GNATCOLL.SQL;           use GNATCOLL.SQL;



procedure Main is


   -- Datebase Description
   --
   DB_Descr : GNATCOLL.SQL.Exec.Database_Description;

   -- Database Connection
   --
   DB : GNATCOLL.SQL.Exec.Database_Connection;


   -- Used to Query the data
   --
   Q : SQL_Query;


begin


   -- Database Description
   --
   DB_Descr := GNATCOLL.SQL.Postgres.Setup ("mydb1", "parallels", "localhost", "MyPassword", 5432);

   -- Database Connection
   --
   DB := DB_Descr.Build_Connection;



   -- Query the data
   --

   Q := SQL_Select
      (Fields => Person.first_name,
       From   => Person);




  Free (DB);  --  for all connections you have opened
  Free (DB_Descr);

   end Main;

当尝试连接到数据库时，进程成功终止。

我不确定应该用于 Select 语句的语法。如果有人能告诉我如何在 GNAT CE 2019 中执行简单的 SELECT * FROM Person; 语句，我们将不胜感激。

谢谢你， 劳埃德

于 20 年 5 月 13 日添加

parallels@localhost gnatcoll_db2ada]$ ls
dborm.py                  gnatcoll-db2ada-main-generate.adb
dbschema.txt              gnatcoll_postgres2ada.adb
gnatcoll_all2ada.adb      gnatcoll_postgres2ada.gpr
gnatcoll_all2ada.gpr      gnatcoll_sqlite2ada.adb
gnatcoll_db2ada.adb       gnatcoll_sqlite2ada.gpr
gnatcoll-db2ada.ads       Makefile
gnatcoll_db2ada.gpr       makefile.setup
[parallels@localhost gnatcoll_db2ada]$ gnatcoll_postgres2ada -dbmodel dschema.txt/home/parallels/Desktop/dschema.txt
bash: gnatcoll_postgres2ada: command not found...
[parallels@localhost gnatcoll_db2ada]$ 

20 年 5 月 15 日添加

prbuild -d -P/home/parallels/Documents/Ada Projects/TEST/default.gpr -XGNATCOLL_OS=unix -XBUILD=PROD -XGNATCOLL_HASPQPREPARE=yes -XGPR_BUILD=static -XLIBRARY_TYPE=static -XXMLADA_BUILD=static -XGNATCOLL_CORE_BUILD=static -XGNATCOLL_BUILD=static /home/parallels/Documents/Ada Projects/TEST/src/main.adb
Compile
   [Ada]          main.adb
Bind
   [gprbind]      main.bexch
   [Ada]          main.ali
Link
   [link]         main.adb
/home/parallels/opt/GNAT/2019/bin/../libexec/gcc/x86_64-pc-linux-gnu/8.3.1/ld: cannot find -lpq
collect2: error: ld returned 1 exit status
gprbuild: link of main.adb failed
gprbuild: failed command was: /home/parallels/opt/GNAT/2019/bin/gcc main.o b__main.o /home/parallels/Documents/Ada Projects/TEST/obj/database_names.o /home/parallels/Documents/Ada Projects/TEST/obj/database.o /home/parallels/gnatcoll-db/postgres/lib/static/libgnatcoll_postgres.a /home/parallels/gnatcoll-db/sql/lib/static/libgnatcoll_sql.a /home/parallels/opt/GNAT/2019/lib/gnatcoll.static/libgnatcoll.a /home/parallels/opt/GNAT/2019/lib/gpr/static/gpr/libgpr.a /home/parallels/opt/GNAT/2019/lib/xmla
da/xmlada_schema.static/libxmlada_schema.a /home/parallels/opt/GNAT/2019/lib/xmlada/xmlada_dom.static/libxmlada_dom.a /home/parallels/opt/GNAT/2019/lib/xmlada/xmlada_sax.static/libxmlada_sax.a /home/parallels/opt/GNAT/2019/lib/xmlada/xmlada_input.static/libxmlada_input_sources.a /home/parallels/opt/GNAT/2019/lib/xmlada/xmlada_unicode.static/libxmlada_unicode.a -lpq -L/home/parallels/Documents/Ada Projects/TEST/obj/ -L/home/parallels/Documents/Ada Projects/TEST/obj/ -L/home/parallels/gnatcoll-db/p
ostgres/lib/static/ -L/home/parallels/opt/GNAT/2019/lib/gnatcoll.static/ -L/home/parallels/opt/GNAT/2019/lib/xmlada/xmlada_dom.static/ -L/home/parallels/opt/GNAT/2019/lib/xmlada/xmlada_sax.static/ -L/home/parallels/opt/GNAT/2019/lib/xmlada/xmlada_unicode.static/ -L/home/parallels/opt/GNAT/2019/lib/xmlada/xmlada_input.static/ -L/home/parallels/opt/GNAT/2019/lib/xmlada/xmlada_schema.static/ -L/home/parallels/opt/GNAT/2019/lib/gpr/static/gpr/ -L/home/parallels/gnatcoll-db/sql/lib/static/ -L/home/par
allels/opt/GNAT/2019/lib/gcc/x86_64-pc-linux-gnu/8.3.1/adalib/ -static-libgcc /home/parallels/opt/GNAT/2019/lib/gcc/x86_64-pc-linux-gnu/8.3.1/adalib/libgnarl.a /home/parallels/opt/GNAT/2019/lib/gcc/x86_64-pc-linux-gnu/8.3.1/adalib/libgnat.a -lrt -lpthread -ldl -Wl,-rpath-link,/home/parallels/opt/GNAT/2019/lib/gcc/x86_64-pc-linux-gnu/8.3.1//adalib -Wl,-z,origin,-rpath,$ORIGIN/:$ORIGIN/../../../..//gnatcoll-db/postgres/lib/static:$ORIGIN/../../../..//opt/GNAT/2019/lib/gnatcoll.static:$ORIGIN/../../
../..//opt/GNAT/2019/lib/xmlada/xmlada_dom.static:$ORIGIN/../../../..//opt/GNAT/2019/lib/xmlada/xmlada_sax.static:$ORIGIN/../../../..//opt/GNAT/2019/lib/xmlada/xmlada_unicode.static:$ORIGIN/../../../..//opt/GNAT/2019/lib/xmlada/xmlada_input.static:$ORIGIN/../../../..//opt/GNAT/2019/lib/xmlada/xmlada_schema.static:$ORIGIN/../../../..//opt/GNAT/2019/lib/gpr/static/gpr:$ORIGIN/../../../..//gnatcoll-db/sql/lib/static:$ORIGIN/../../../..//opt/GNAT/2019/lib/gcc/x86_64-pc-linux-gnu/8.3.1/adalib -o main
[2020-05-15 14:56:50] process exited with status 4, 100% (30/30), elapsed time: 02.34s

于 20 年 5 月 17 日添加

[SQL.ERROR] FATAL:  Ident authentication failed for user "postgres"
_SQL.ERROR_ FATAL:  Ident authentication failed for user "postgres"
_SQL.ERROR_  params="dbname='mydb1' user='postgres' host='localhost' sslmode=allow" ()
[SQL.ERROR] Failed to execute SELECT persons.person_uid, persons.first_name, persons.last_name, persons.gender, persons.email, persons.date_of_birth, persons.country_of_birth FROM persons  error=No connection to database
FAILED
[2020-05-17 19:30:04] process terminated successfully, elapsed time: 00.19s

于 2020 年 5 月 29 日添加

home/parallels/Documents/Ada Projects/Connect to a DB/obj/main
[SQL.ERROR] select failed: SELECT persons.person_uid, persons.first_name, persons.last_name, persons.gender, persons.email, persons.date_of_birth, persons.country_of_birth FROM persons PGRES_FATAL_ERROR ERROR:  relation "persons" does not exist
_SQL.ERROR_ LINE 1: ...persons.date_of_birth, persons.country_of_birth FROM persons
_SQL.ERROR_                                                                 ^
FAILED
[2020-05-29 22:40:11] process terminated successfully, elapsed time: 00.19s

postgres=# select * from persons;
              person_uid              | first_name | last_name  | gender |            email             | date_of_birth | country_of_birth 
--------------------------------------+------------+------------+--------+------------------------------+---------------+------------------
 afbf64be-e7d5-45a1-b8fb-1a9fd66e2765 | Audrie     | Vasyukov   | Female | avasyukovd6@domainmarket.com | 1988-11-24    | Guatemala
 ffda7264-1e54-428b-ae68-9ddb7b97702a | Nefen      | Philippard | Male   | nphilippardd7@economist.com  | 2006-11-08    | Russia
 169d5fb9-8d40-451e-8b02-cd1c3639fbed | Leonore    | Garthland  | Female | lgarthlandd8@furl.net        | 1991-03-23    | Canada
 e34f4f21-524c-4134-81d6-7fd1fd9a7537 | Yank       | Turfitt    | Male   | yturfittd9@exblog.jp         | 1990-02-07    | China
 57336d0e-34f2-4166-a100-7b468e96a521 | Benn       | Pawley     | Male   | bpawleyda@indiegogo.com      | 2006-10-28    | Russia
 b54a8411-3674-4432-b896-aaf35a10919b | Tod        | Easen      | Male   | teasend4@php.net             | 1990-08-24    | China
(6 rows)

Answer 1

user manual 声明您必须首先生成代表与您交互的数据库的实体（表、字段等）的 Ada 数据类型，才能使用像 SQL_Select 这样的函数。这可以使用gnatcoll_db2ada 实用程序来完成（参见here）；通过对数据库的某种反思或通过提供手写模式（用户手册中的示例）。以下是我自己创建示例的步骤。

安装依赖：

$ sudo apt-get install postgresql libpq-dev

创建一个数据库用户（这里：deedee）：

$ sudo -u postgres bash
postgres@debian: $ createuser --pwprompt deedee

克隆gnatcoll-db:

$ git clone https://github.com/AdaCore/gnatcoll-db.git

构建并安装gnatcoll-sql:

gnatcoll-db/sql $ make setup
gnatcoll-db/sql $ make
gnatcoll-db/sql $ sudo bash -c "PATH=$PATH:/opt/GNAT/2019/bin make install"

构建并安装gnatcoll-postgress:

gnatcoll-db/postgress $ make setup
gnatcoll-db/postgress $ make
gnatcoll-db/postgress $ sudo bash -c "PATH=$PATH:/opt/GNAT/2019/bin make install"

构建并安装gnatcoll_db2ada:

gnatcoll-db/gnatcoll_db2ada $ make setup DB_BACKEND=postgres
gnatcoll-db/gnatcoll_db2ada $ make
gnatcoll-db/gnatcoll_db2ada $ sudo bash -c "PATH=$PATH:/opt/GNAT/2019/bin make install"

该实用程序将安装在所有其他 GNAT 程序旁边：

$ which gnatcoll_postgres2ada
/opt/GNAT/2019/bin/gnatcoll_postgres2ada

为了使用该实用程序，我首先使用您提供的数据创建了一个小型数据库。我使用命令重新创建了表persons：

$ sudo -u postgres bash
postgres@debian: $ createdb mydb1
postgres@debian: $ psql mydb1 < persons.sql

与

persons.sql

CREATE EXTENSION IF NOT EXISTS "uuid-ossp";

CREATE TYPE gender AS ENUM ('Male', 'Female');

CREATE TABLE persons (
    person_uid        uuid DEFAULT uuid_generate_v4 () PRIMARY KEY,
    first_name        VARCHAR (20) NOT NULL,
    last_name         VARCHAR (20) NOT NULL,
    gender            gender       NOT NULL,
    email             VARCHAR (50) NOT NULL,
    date_of_birth     DATE         NOT NULL,
    country_of_birth  VARCHAR (20) NOT NULL
);

INSERT INTO persons (
    first_name, 
    last_name, 
    gender, 
    email, 
    date_of_birth, 
    country_of_birth
)
VALUES
   ('Audrie' , 'Vasyukov'  , 'Female', 'avasyukovd6@domainmarket.com', '1988-11-24', 'Guatemala'),
   ('Nefen'  , 'Philippard', 'Male'  , 'nphilippardd7@economist.com' , '2006-11-08', 'Russia'   ),
   ('Leonore', 'Garthland' , 'Female', 'lgarthlandd8@furl.net'       , '1991-03-23', 'Canada'   ),
   ('Yank'   , 'Turfitt'   , 'Male'  , 'yturfittd9@exblog.jp'        , '1990-02-07', 'China'    ),
   ('Benn'   , 'Pawley'    , 'Male'  , 'bpawleyda@indiegogo.com'     , '2006-10-28', 'Russia'   ),
   ('Tod'    , 'Easen'     , 'Male'  , 'teasend4@php.net'            , '1990-08-24', 'China'    );

GRANT SELECT ON persons TO deedee;

然后我创建了一个数据库模式（参见用户手册）并生成了 Ada 代码：

$ gnatcoll_postgres2ada -dbmodel dschema.txt
$ ls
database.adb  database.ads  database_names.ads  dschema.txt

与

dschema.txt

| TABLE             | persons |          || The contents of person |
| person_uid        | TEXT    | PK       || Auto-generated id      |
| first_name        | TEXT    | NOT NULL || First name             |
| last_name         | TEXT    | NOT NULL || Last name              |
| gender            | TEXT    | NOT NULL || Gender                 |
| email             | TEXT    | NOT NULL || E-mail address         |
| date_of_birth     | DATE    | NOT NULL || Date of birth          |
| country_of_birth  | TEXT    | NOT NULL || Country of birth       |

我终于添加了一个跟踪配置文件（基于 GNATcoll 用户手册中的示例），修改了您的示例代码并使其与我自己的表一起使用：

.gnatdebug（将跟踪信息写入标准错误；由>&2 指示）

>&2
SQL.yes
SQL.SELECT=yes
SQL.LITE=yes

default.gpr

with "gnatcoll_postgres.gpr";

project Default is
   for Source_Dirs use ("src");
   for Object_Dir use "obj";
   for Main use ("main.adb");
end Default;

ma​​in.adb

with Ada.Text_IO;            use Ada.Text_IO;
with GNATCOLL.Traces;        use GNATCOLL.Traces;
with GNATCOLL.SQL.Postgres;  use GNATCOLL.SQL.Postgres;
with GNATCOLL.SQL.Exec;      use GNATCOLL.SQL.Exec;
with GNATCOLL.VFS;           use GNATCOLL.VFS;
with GNATCOLL.SQL.Inspect;   use GNATCOLL.SQL.Inspect;
with GNATCOLL.SQL;           use GNATCOLL.SQL;
with Database;

procedure Main is

   -- Datebase Description
   DB_Descr : GNATCOLL.SQL.Exec.Database_Description;

   -- Database Connection
   DB : GNATCOLL.SQL.Exec.Database_Connection;

   -- Used to Query the data
   Q : SQL_Query;

begin

   --  Enable tracing, so we can see if something goes wrong.
   GNATCOLL.Traces.Parse_Config_File (".gnatdebug");

   -- Database description.
   DB_Descr := GNATCOLL.SQL.Postgres.Setup
     (Database => "mydb1",
      User     => "deedee",
      Host     => "localhost",
      Password => "xxxx");

   -- Database connection.
   DB := DB_Descr.Build_Connection;

   -- Define the query.
   Q := SQL_Select
     (Fields =>
        Database.Persons.Person_Uid        &  --  0
        Database.Persons.First_Name        &  --  1
        Database.Persons.Last_Name         &  --  2
        Database.Persons.Gender            &  --  3
        Database.Persons.Email             &  --  4
        Database.Persons.Date_Of_Birth     &  --  5
        Database.Persons.Country_Of_Birth,    --  6
      From => Database.Persons);

   declare
      R : Forward_Cursor;
   begin

      --  Perform the actual query, show results if OK.
      R.Fetch (DB, Q);
      if Success (DB) then
         while Has_Row (R) loop

            Put_Line ("UUID . . : " & Value (R, 0));
            Put_Line ("Name . . : " & Value (R, 1) & " " & Value (R, 2));
            Put_Line ("Gender . : " & Value (R, 3));
            Put_Line ("E-Mail . : " & Value (R, 4));
            Put_Line ("Birth. . : " & Value (R, 5) & ", " & Value (R, 6));
            New_Line;

            Next (R);
         end loop;

      else
         Put_Line ("FAILED");
      end if;
   end;

   Free (DB);  --  for all connections you have opened
   Free (DB_Descr);

   GNATCOLL.Traces.Finalize;

end Main;

构建和输出

$ gprbuild -P default.gpr
[...]
$ ./obj/main
[SQL.SELECT] SELECT persons.person_uid, persons.first_name, persons.last_name, persons.gender, persons.email, persons.date_of_birth, persons.country_of_birth FROM persons (6 tuples) PGRES_TUPLES_OK
UUID . . : 564b6d18-5f99-4d6b-8098-d5ce79910107
Name . . : Audrie Vasyukov
Gender . : Female
E-Mail . : avasyukovd6@domainmarket.com
Birth. . : 1988-11-24, Guatemala

UUID . . : a4c2743a-40ad-409e-9af7-f21e7b91da05
Name . . : Nefen Philippard
Gender . : Male
E-Mail . : nphilippardd7@economist.com
Birth. . : 2006-11-08, Russia

UUID . . : 04aa6123-b317-4be3-a1af-8a01d43ee60f
Name . . : Leonore Garthland
Gender . : Female
E-Mail . : lgarthlandd8@furl.net
Birth. . : 1991-03-23, Canada

UUID . . : e43ec5ef-3cd2-4d3c-8f3e-106b7c2f2ccf
Name . . : Yank Turfitt
Gender . : Male
E-Mail . : yturfittd9@exblog.jp
Birth. . : 1990-02-07, China

UUID . . : 3e1d6431-62d5-4d4b-8333-a92a66575f9f
Name . . : Benn Pawley
Gender . : Male
E-Mail . : bpawleyda@indiegogo.com
Birth. . : 2006-10-28, Russia

UUID . . : ae60db02-298a-43d3-81a2-59fcf610c045
Name . . : Tod Easen
Gender . : Male
E-Mail . : teasend4@php.net
Birth. . : 1990-08-24, China

---

附录

我使用默认（非自定义）基于主机的身份验证 (hba) 文件。

pg_hba.conf

# Database administrative login by Unix domain socket
local   all             postgres                                peer

# TYPE  DATABASE        USER            ADDRESS                 METHOD

# "local" is for Unix domain socket connections only
local   all             all                                     peer
# IPv4 local connections:
host    all             all             127.0.0.1/32            md5
# IPv6 local connections:
host    all             all             ::1/128                 md5
# Allow replication connections from localhost, by a user with the
# replication privilege.
local   replication     all                                     peer
host    replication     all             127.0.0.1/32            md5
host    replication     all             ::1/128                 md5