postgresql导出的表结构在语句上会和mysql有些差异，因此当我们在mysql命令行中执行的时候，会有警告和错误提示，但是最终还是会将表生成成功，这里将表结构和数据分别单独导出，而且使用的语法和方法都不一样。
导出表结构直接使用postgresql命令pg_dump，而导出数据使用psql命令的copy。在mysql中导入表结构，我们执行source /path/to/table.sql，我们导入的表数据是单独的，而且是格式化的数据，我们通过load data local infile语句导入，需要指定列分隔符，以及行分隔符。
1、检查表结构和数据
postgres=# \c test
You are now connected to database "test" as user "postgres".
test=# \dt
List of relations
Schema | Name | Type | Owner
--------+---------+-------+----------
public | xx_user | table | postgres
(1 row)
test=# \d xx_user
Table "public.xx_user"
Column | Type | Collation | Nullable | Default
--------+-----------------------+-----------+----------+-------------------------------------
id | integer | | not null | nextval('xx_user_id_seq'::regclass)
name | character varying(20) | | |
mobile | character varying(20) | | |
birth | date | | |
Indexes:
"xx_user_pkey" PRIMARY KEY, btree (id)
test=# select * from xx_user;
id | name | mobile | birth
----+------+-------------+------------
1 | aaa | 13886604139 | 1987-08-24
2 | bbb | 15342525980 | 1980-01-01
3 | ccc | 18761598031 | 1992-09-29
4 | ddd | 15910909870 | 1990-09-21
5 | eee | 15900909890 | 1990-02-26
(5 rows)
2、导出表结构
[postgres@server ~]$ pg_dump --verbose --schema-only --table=xx_user --db=test --file=/home/postgres/user.sql
pg_dump: last built-in OID is 16383
pg_dump: reading extensions
pg_dump: identifying extension members
pg_dump: reading schemas
pg_dump: reading user-defined tables
pg_dump: reading user-defined functions
pg_dump: reading user-defined types
pg_dump: reading procedural languages
pg_dump: reading user-defined aggregate functions
pg_dump: reading user-defined operators
pg_dump: reading user-defined access methods
pg_dump: reading user-defined operator classes
pg_dump: reading user-defined operator families
pg_dump: reading user-defined text search parsers
pg_dump: reading user-defined text search templates
pg_dump: reading user-defined text search dictionaries
pg_dump: reading user-defined text search configurations
pg_dump: reading user-defined foreign-data wrappers
pg_dump: reading user-defined foreign servers
pg_dump: reading default privileges
pg_dump: reading user-defined collations
pg_dump: reading user-defined conversions
pg_dump: reading type casts
pg_dump: reading transforms
pg_dump: reading table inheritance information
pg_dump: reading event triggers
pg_dump: finding extension tables
pg_dump: finding inheritance relationships
pg_dump: reading column info for interesting tables
pg_dump: finding the columns and types of table "public.xx_user"
pg_dump: finding default expressions of table "public.xx_user"
pg_dump: flagging inherited columns in subtables
pg_dump: reading indexes
pg_dump: reading indexes for table "public.xx_user"
pg_dump: flagging indexes in partitioned tables
pg_dump: reading extended statistics
pg_dump: reading constraints
pg_dump: reading triggers
pg_dump: reading rewrite rules
pg_dump: reading policies
pg_dump: reading row security enabled for table "public.xx_user_id_seq"
pg_dump: reading policies for table "public.xx_user_id_seq"
pg_dump: reading row security enabled for table "public.xx_user"
pg_dump: reading policies for table "public.xx_user"
pg_dump: reading publications
pg_dump: reading publication membership
pg_dump: reading publication membership for table "public.xx_user"
pg_dump: reading subscriptions
pg_dump: reading dependency data
pg_dump: saving encoding = UTF8
pg_dump: saving standard_conforming_strings = on
pg_dump: saving search_path =
pg_dump: creating TABLE "public.xx_user"
pg_dump: creating SEQUENCE "public.xx_user_id_seq"
pg_dump: creating SEQUENCE OWNED BY "public.xx_user_id_seq"
pg_dump: creating DEFAULT "public.xx_user id"
pg_dump: creating CONSTRAINT "public.xx_user xx_user_pkey"
我们可以看看生成的sql语句：
--
-- PostgreSQL database dump
--
-- Dumped from database version 11.4
-- Dumped by pg_dump version 11.4
-- Started on 2019-07-21 08:33:09 CST
SET statement_timeout = 0;
SET lock_timeout = 0;
SET idle_in_transaction_session_timeout = 0;
SET client_encoding = 'UTF8';
SET standard_conforming_strings = on;
SELECT pg_catalog.set_config('search_path', '', false);
SET check_function_bodies = false;
SET xmloption = content;
SET client_min_messages = warning;
SET row_security = off;
SET default_tablespace = '';
SET default_with_oids = false;
--
-- TOC entry 197 (class 1259 OID 16387)
-- Name: xx_user; Type: TABLE; Schema: public; Owner: postgres
--
CREATE TABLE public.xx_user (
id integer NOT NULL,
name character varying(20),
mobile character varying(20),
birth date
);
ALTER TABLE public.xx_user OWNER TO postgres;
--
-- TOC entry 196 (class 1259 OID 16385)
-- Name: xx_user_id_seq; Type: SEQUENCE; Schema: public; Owner: postgres
--
CREATE SEQUENCE public.xx_user_id_seq
AS integer
START WITH 1
INCREMENT BY 1
NO MINVALUE
NO MAXVALUE
CACHE 1;
ALTER TABLE public.xx_user_id_seq OWNER TO postgres;
--
-- TOC entry 3086 (class 0 OID 0)
-- Dependencies: 196
-- Name: xx_user_id_seq; Type: SEQUENCE OWNED BY; Schema: public; Owner: postgres
--
ALTER SEQUENCE public.xx_user_id_seq OWNED BY public.xx_user.id;
--
-- TOC entry 2957 (class 2604 OID 16390)
-- Name: xx_user id; Type: DEFAULT; Schema: public; Owner: postgres
--
ALTER TABLE ONLY public.xx_user ALTER COLUMN id SET DEFAULT nextval('public.xx_user_id_seq'::regclass);
--
-- TOC entry 2959 (class 2606 OID 16392)
-- Name: xx_user xx_user_pkey; Type: CONSTRAINT; Schema: public; Owner: postgres
--
ALTER TABLE ONLY public.xx_user
ADD CONSTRAINT xx_user_pkey PRIMARY KEY (id);
-- Completed on 2019-07-21 08:33:09 CST
--
-- PostgreSQL database dump complete
--
这里使用的是postgresql11.4，通过pg_dump导出表结构，从语句上看到，我们生成的表前面带有前缀"public."，这个前缀如果在mysql中执行会报错，因此我们需要将"public."这个前缀在sql文件中给去掉，暂时没有找到如何在导出的时候去掉这个前缀：“public.”，因此只能手工处理一下。
3、导出数据
[postgres@server ~]$ psql
psql (11.4)
Type "help" for help.
postgres=# \c test
You are now connected to database "test" as user "postgres".
test=# copy xx_user to '/home/postgres/user.txt' with (delimiter ',');
COPY 5
test=#
导出5条记录，我们将导出的数据保存在/home/postgres/user.txt文本文件中，数据列之间用逗号“,”分隔。
[postgres@server ~]$ cat user.txt
1,aaa,13886604139,1987-08-24
2,bbb,15342525980,1980-01-01
3,ccc,18761598031,1992-09-29
4,ddd,15910909870,1990-09-21
5,eee,15900909890,1990-02-26
4、在mysql中导入表结构：
mysql> source /home/postgres/user.sql
ERROR 1193 (HY000): Unknown system variable 'statement_timeout'
ERROR 1193 (HY000): Unknown system variable 'lock_timeout'
ERROR 1193 (HY000): Unknown system variable 'idle_in_transaction_session_timeout'
ERROR 1193 (HY000): Unknown system variable 'client_encoding'
ERROR 1193 (HY000): Unknown system variable 'standard_conforming_strings'
ERROR 1305 (42000): FUNCTION pg_catalog.set_config does not exist
ERROR 1193 (HY000): Unknown system variable 'check_function_bodies'
ERROR 1193 (HY000): Unknown system variable 'xmloption'
ERROR 1193 (HY000): Unknown system variable 'client_min_messages'
ERROR 1193 (HY000): Unknown system variable 'row_security'
ERROR 1193 (HY000): Unknown system variable 'default_with_oids'
Query OK, 0 rows affected (0.02 sec)
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'SEQUENCE xx_user_id_seq
AS integer
START WITH 1
INCREMENT BY 1
N' at line 1
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'SEQUENCE xx_user_id_seq OWNED BY xx_user.id' at line 1
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'xx_user ALTER COLUMN id SET DEFAULT nextval('xx_user_id_seq'::regclass)' at line 1
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'public.xx_user
ADD CONSTRAINT xx_user_pkey PRIMARY KEY (id)' at line 1
mysql> desc xx_user;
+--------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+--------+-------------+------+-----+---------+-------+
| id | int(11) | NO | | NULL | |
| name | varchar(20) | YES | | NULL | |
| mobile | varchar(20) | YES | | NULL | |
| birth | date | YES | | NULL | |
+--------+-------------+------+-----+---------+-------+
4 rows in set (0.05 sec)
这一步需要注意的是，我们在导出表结构的时候说过的问题，因为sql文件中，表名前面会带有"public."这个前缀，因此需要人为去掉，否则导入表结构会出现错误。
5、在mysql中导入数据
mysql> load data local infile '/home/postgres/user.txt' into table xx_user fields terminated by ',' lines terminated by '\n';
Query OK, 5 rows affected (0.02 sec)
Records: 5 Deleted: 0 Skipped: 0 Warnings: 0
mysql> select * from xx_user;
+----+------+-------------+------------+
| id | name | mobile | birth |
+----+------+-------------+------------+
| 1 | aaa | 13886604139 | 1987-08-24 |
| 2 | bbb | 15342525980 | 1980-01-01 |
| 3 | ccc | 18761598031 | 1992-09-29 |
| 4 | ddd | 15910909870 | 1990-09-21 |
| 5 | eee | 15900909890 | 1990-02-26 |
+----+------+-------------+------------+
5 rows in set (0.00 sec)
---------------------