介绍:

    也许大家都难以理解,这么重要的数据为啥不备份(或者备份不可用)?而且还任性的drop table了。显然有备份是最好的，但是它们并不总是可用的。这种情况令人恐惧，但并非毫无希望。在许多情况下，可以恢复数据库或表中的几乎所有数据。恢复计划取决于InnoDB是否将所有数据保存在一个ibdata1中，还是每个表都有自己的表空间。本文将考虑innodb_file_per_table=OFF的情况。

drop 表恢复其他方法:

本文重要部分:

环境:

  • 时间:#Sat Aug 4 19:37:24 CST 2018
  • CentOS Linux release 7.2.1511 (Core)
  • MySQL:5.7.23-log
  • 使用工具:undrop-for-innodb

1.工具安装

  • 依赖包安装
yum install -y make gcc flex bison
  • 下载工具包(github)
#cd /opt/

[root@db13_19:55:25 /opt]

#git clone https://github.com/twindb/undrop-for-innodb.git

Cloning into 'undrop-for-innodb'...

Resolving deltas: 100% (77/77), done.
  • make
#cd /opt/undrop-for-innodb

#make

....

....

[root@db13_20:39:43 /opt/undrop-for-innodb]

#ll

total 2920

-rw-r--r-- 1 root root    6271 Aug  4 19:55 check_data.c

-rw-r--r-- 1 root root   66128 Aug  4 20:39 check_data.o

-rwxr-xr-x 1 root root  727801 Aug  4 20:39 c_parser

-rw-r--r-- 1 root root   28587 Aug  4 19:55 c_parser.c

-rw-r--r-- 1 root root 1030296 Aug  4 20:39 c_parser.o

drwxr-xr-x 2 root root      92 Aug  4 19:55 dictionary

-rw-r--r-- 1 root root    1978 Aug  4 19:55 fetch_data.sh

drwxr-xr-x 2 root root    4096 Aug  4 19:55 include

-rw-r--r-- 1 root root    8936 Aug  4 19:55 innochecksum.c

-rwxr-xr-x 1 root root   36343 Aug  4 20:39 innochecksum_changer

-rw-r--r-- 1 root root  154459 Aug  4 20:39 lex.yy.c

-rw-r--r-- 1 root root   18047 Aug  4 19:55 LICENSE

-rw-r--r-- 1 root root    1942 Aug  4 19:55 Makefile

-rw-r--r-- 1 root root   16585 Aug  4 19:55 print_data.c

-rw-r--r-- 1 root root  127176 Aug  4 20:39 print_data.o

-rw-r--r-- 1 root root    3464 Aug  4 19:55 README.md

-rwxr-xr-x 1 root root    1536 Aug  4 19:55 recover_dictionary.sh

drwxr-xr-x 2 root root    4096 Aug  4 19:55 sakila

-rw-r--r-- 1 root root  103506 Aug  4 20:39 sql_parser.c

-rw-r--r-- 1 root root    8462 Aug  4 19:55 sql_parser.l

-rw-r--r-- 1 root root  296840 Aug  4 20:39 sql_parser.o

-rw-r--r-- 1 root root   26355 Aug  4 19:55 sql_parser.y

-rwxr-xr-x 1 root root   61725 Aug  4 20:39 stream_parser

-rw-r--r-- 1 root root   23103 Aug  4 19:55 stream_parser.c

-rw-r--r-- 1 root root  109304 Aug  4 20:39 stream_parser.o

-rw-r--r-- 1 root root   14764 Aug  4 19:55 sys_parser.c

-rw-r--r-- 1 root root    2182 Aug  4 19:55 tables_dict.c

-rw-r--r-- 1 root root   40264 Aug  4 20:39 tables_dict.o

-rwxr-xr-x 1 root root    6629 Aug  4 19:55 test.sh

drwxr-xr-x 3 root root      42 Aug  4 19:55 vagrant

[root@db13_20:39:57 /opt/undrop-for-innodb]
  • 增加用于恢复表结构的工具sys_parser(官方文档未使用):
#gcc `/usr/local/mysql57/bin/mysql_config --cflags` `/usr/local/mysql57/bin/mysql_config --libs` -o sys_parser sys_parser.c

 注:mysql_basedir: /usr/local/mysql57/bin/

2.表数据生成和drop表

  • 初始化一个新实例:
[root@db212_20:58:44 /data/57mysql]

#mkdir mysql3507/{data,logs,tmp} -p

#chown -R mysql:mysql mysql3507

[root@db212_21:07:34 /3507]

\\复制my3507.cnf到mysql3507下

#ln -s /data/57mysql/mysql3507/ /3507

#/usr/local/mysql57/bin/mysqld --defaults-file=/3507/my3507.cnf --initialize-insecure

#/usr/local/mysql57/bin/mysqld --defaults-file=/3507/my3507.cnf&

[1] 11669

//取初始密码并登录:

/usr/local/mysql57/bin/mysql -S /tmp/mysql3507.sock -uroot 
(unknown)@localhost [(none)]>alter user user() identified by '*****';

root@localhost [(none)]>CREATE DATABASE wenyz;

root@localhost [(none)]>use wenyz;

Database changed

//创建表

root@localhost [wenyz]>CREATE TABLE `t2` (

    ->   `id` int(10) unsigned NOT NULL AUTO_INCREMENT,

    ->   `ti` varchar(100) NOT NULL,

    ->   `date` date DEFAULT NULL,

    ->   PRIMARY KEY (`id`)

    -> ) ENGINE=InnoDB AUTO_INCREMENT=4079859 DEFAULT CHARSET=utf8;

Query OK, 0 rows affected (0.01 sec)

//造数据

root@localhost [wenyz]>insert into t2(ti,date) values(substring(MD5(RAND()),floor(RAND()*26)+1,15),now()) ;

Records: 448  Duplicates: 0  Warnings: 0

//查看数据行数和checksum值

root@localhost [wenyz]>select count(*) from t2;

+----------+

| count(*) |

+----------+

|      896 |

+----------+

root@localhost [wenyz]>checksum table t2;

+----------+------------+

| Table    | Checksum   |

+----------+------------+

| wenyz.t2 | 3458542072 |

+----------+------------+

//DROP 表

root@localhost [wenyz]>drop table t2;

Query OK, 0 rows affected (0.01 sec)

3.利用stream_parser将ibdata1文件导出成page文件

#cd /opt/undrop-for-innodb/

[root@db212_21:25:52 /opt/undrop-for-innodb]

#./stream_parser -f /3507/data/ibdata1

Opening file: /3507/data/ibdata1

File information:

....

Size to process:                 104857600 (100.000 MiB)

Size to process:                 104857600 (100.000 MiB)

time of last access:            1533388916 Sat Aug  4 21:21:56 2018

time of last modification:      1533388917 Sat Aug  4 21:21:57 2018

time of last status change:     1533388917 Sat Aug  4 21:21:57 2018

total size, in bytes:            104857600 (100.000 MiB)

Size to process:                 104857600 (100.000 MiB)

All workers finished in 0 sec

4.恢复表结构 [ Top ]

这里引入官方的一段描述:

InnoDB stores all data in B+tree indexes. A table has one clustered index PRIMARY, all fields are stored there. Thus, if the table has secondary keys, each key has an index. Each index is identified by index_id.

Consequently, if we want to recover a table, we have to find all pages that belong to a particular index_id.

  • 接下来我们先来看看怎么找到table id和INDEX_ID(page文件编号)的，理解原理后再用程序跑一次，导入到临时数据库中

  • 手工查找table id
    观察以下结果中,wenyz/t2后的40,即为table id
[root@db212_21:25:55 /opt/undrop-for-innodb]

#./c_parser -4Df pages-ibdata1/FIL_PAGE_INDEX/0000000000000001.page -t dictionary/SYS_TABLES.sql | grep 'wenyz/t2'

000000000521    3B00000149047E  SYS_TABLES  "wenyz/t2"  40  3   33  0   64  ""  0

SET FOREIGN_KEY_CHECKS=0;

LOAD DATA LOCAL INFILE '000000000521    3B00000149047E  SYS_TABLES  "wenyz/t2"  40  3   33  0   64  ""  0
  • 通过table id查看page文件编号
    观察以下结果中40后的41,即为INDEX_ID(page文件编号)
[root@db212_21:29:54 /opt/undrop-for-innodb]

#./c_parser -4Df pages-ibdata1/FIL_PAGE_INDEX/0000000000000003.page -t dictionary/SYS_INDEXES.sql | grep '40'

000000000521    3B0000014903A2  SYS_INDEXES 40  41  "PRIMARY"   1   3   0   4294967295

SET FOREIGN_KEY_CHECKS=0;

000000000521    3B0000014903A2  SYS_INDEXES 40  41  "PRIMARY"   1   3   0   4294967295
  • 用程序恢复字典信息:编辑mysql登录信息.
[root@db212_21:57:04 /opt/undrop-for-innodb]  

//将文件中三处mysql替换成/usr/local/mysql57/bin/mysql --login-path=p3507

#vi recover_dictionary.sh

 43 /usr/local/mysql57/bin/mysql --login-path=p3507 -e "CREATE DATABASE IF NOT EXISTS test"

...

 50 /usr/local/mysql57/bin/mysql --login-path=p3507 test < dictionary/$t.sql

...

 58 /usr/local/mysql57/bin/mysql --login-path=p3507 test < dumps/default/$t.sql
  • 执行/recover_dictionary.sh,恢复字典信息
[root@db212_22:13:57 /opt/undrop-for-innodb]

#./recover_dictionary.sh

Generating dictionary tables dumps... OK

Creating test database ... OK

Creating dictionary tables in database test:

SYS_TABLES ... OK

SYS_COLUMNS ... OK

SYS_INDEXES ... OK

SYS_FIELDS ... OK

All OK

Loading dictionary tables data:

SYS_TABLES ... 52 recs OK

SYS_COLUMNS ... 284 recs OK

SYS_INDEXES ... 68 recs OK

SYS_FIELDS ... 90 recs OK

All OK

[root@db212_22:14:02 /opt/undrop-for-innodb]
  • 登录mysql查看信息字典信息:
mysql --login-path=p3507

root@localhost [(none)]>use test;

Database changed

root@localhost [test]>select * from SYS_TABLES where name like 'wenyz/t2%';

+----------+----+--------+------+--------+---------+--------------+-------+

| NAME     | ID | N_COLS | TYPE | MIX_ID | MIX_LEN | CLUSTER_NAME | SPACE |

+----------+----+--------+------+--------+---------+--------------+-------+

| wenyz/t2 | 40 |      3 |   33 |      0 |      64 |              |     0 |

+----------+----+--------+------+--------+---------+--------------+-------+

1 row in set (0.00 sec)

root@localhost [test]>select * from SYS_INDEXES where table_id=40;

+----------+----+---------+----------+------+-------+------------+

| TABLE_ID | ID | NAME    | N_FIELDS | TYPE | SPACE | PAGE_NO    |

+----------+----+---------+----------+------+-------+------------+

|       40 | 41 | PRIMARY |        1 |    3 |     0 | 4294967295 |

+----------+----+---------+----------+------+-------+------------+

//注意记录上表中id,此ID为INDEX_ID(page文件编号)等会表数据恢复要使用

1 row in set (0.00 sec)

root@localhost [test]>
./sys_parser -h 127.0.0.1 -u root -p xxxx -d test wenyz/t2

./sys_parser: error while loading shared libraries: libmysqlclient.so.20: cannot open shared object file: No such file or directory

#ln -s /opt/mysql-5.7.23-linux-glibc2.12-x86_64/lib/libmysqlclient.so.20 /usr/lib64/libmysqlclient.so.20

[root@db212_22:23:25 /opt/undrop-for-innodb]

#./sys_parser -h 127.0.0.1 -u root -p zstzst -d test wenyz/t2

CREATE TABLE `t2`(

    `id` INT UNSIGNED NOT NULL,

    `ti` VARCHAR(100) CHARACTER SET 'utf8' COLLATE 'utf8_general_ci' NOT NULL,

    `date` DATE,

    PRIMARY KEY (`id`)

) ENGINE=InnoDB;

[root@db212_22:23:30 /opt/undrop-for-innodb]
  • 将恢复的表结构存到/tmp/t2.sql
#cat /tmp/t2.sql

CREATE TABLE `t2`(

    `id` INT UNSIGNED NOT NULL,

    `ti` VARCHAR(100) CHARACTER SET 'utf8' COLLATE 'utf8_general_ci' NOT NULL,

    `date` DATE,

    PRIMARY KEY (`id`)

) ENGINE=InnoDB;

[root@db212_22:26:20 /opt/undrop-for-innodb]

5.表数据恢复 [ Top ]

  • 查看数据是否存在

以下命令中使用的0000000000000041.page为上面提到的INDEX_ID(page文件编号),/tmp/t2.sql为上面恢复的表结构.

[root@db212_22:33:44 /opt/undrop-for-innodb]

#./c_parser -6f pages-ibdata1/FIL_PAGE_INDEX/0000000000000041.page -t /tmp/t2.sql |head -2

-- Page id: 459, Format: COMPACT, Records list: Valid, Expected records: (180 180)

000000000507    A7000001210110  t2  4079859 "d553635af1a3b" "2018-08-04"

000000000508    A8000001230110  t2  4079860 "44d64b99fc30d1b"   "2018-08-04"

[root@db212_22:33:44 /opt/undrop-for-innodb]
  • 利用c_parser将0000000000000041.page导出成可执行sql
//注意:此处几个文件名程序把导出的两个数据文件的文件名关系是写死的,以下dumps/default/t2中的t2是需要和表名一致,在t2_load.sql中会引用此文件路经.

./c_parser -6f pages-ibdata1/FIL_PAGE_INDEX/0000000000000041.page -t /tmp/t2.sql > dumps/default/t2 2> dumps/default/t2_load.sql

#cd dumps/default/

[root@db212_22:41:01 /opt/undrop-for-innodb/dumps/default]

#ll

total 132

-rw-r--r-- 1 root root 21232 Aug  4 22:14 SYS_COLUMNS

...

-rw-r--r-- 1 root root 62923 Aug  4 22:40 t2

-rw-r--r-- 1 root root   308 Aug  4 22:40 t2_load.sql

[root@db212_22:41:04 /opt/undrop-for-innodb/dumps/default]

#cat t2_load.sql

SET FOREIGN_KEY_CHECKS=0;

LOAD DATA LOCAL INFILE '/opt/undrop-for-innodb/dumps/default/t2' REPLACE INTO TABLE `t2` FIELDS TERMINATED BY '\t' OPTIONALLY ENCLOSED BY '"' LINES STARTING BY 't2\t' (`id`, `ti`, `date`);

-- STATUS {"records_expected": 896, "records_dumped": 896, "records_lost": false} STATUS END
  • 将表结构t2.sql和表数据t2和t2_load.sql导入数据库
root@localhost [test]>source /tmp/t2.sql

Query OK, 0 rows affected (0.02 sec)

root@localhost [test]>source /opt/undrop-for-innodb/dumps/default/t2_load.sql

Query OK, 0 rows affected (0.00 sec)

Query OK, 896 rows affected (0.01 sec)

Records: 896  Deleted: 0  Skipped: 0  Warnings: 0

root@localhost [test]>select count(*) from t2;

+----------+

| count(*) |

+----------+

|      896 |

+----------+

1 row in set (0.00 sec)

root@localhost [test]>checksum table t2;

+---------+------------+

| Table   | Checksum   |

+---------+------------+

| test.t2 | 3458542072 |

+---------+------------+

1 row in set (0.00 sec)

root@localhost [test]>

//drop前数据信息对比:

root@localhost [wenyz]>select count(*) from t2;

+----------+

| count(*) |

+----------+

|      896 |

+----------+

1 row in set (0.00 sec)

root@localhost [wenyz]>checksum table t2;

+----------+------------+

| Table    | Checksum   |

+----------+------------+

| wenyz.t2 | 3458542072 |

+----------+------------+

1 row in set (0.00 sec)
  • 至此数据已经完全恢复.

6.未解决的问题 [ Top ]

问题1.
innodb(非独立表空间)情况,drop表后,用工具读ibdata1对应数据页文件,如果是这个表大于350行左右的数据,页文件是存在的,但小于350行左右,页文件就不存在(drop前页文件是存在的).这是个什么原因呢
脚本输出信息:

以下为精简信息,完整输出信息请点击下载文本(由于不能上传txt,所以在文件名后面加了sh,下载后请删除.sh):
320行,没有drop记录:
320行,drop
640行,drop



select count(*) from t2

640

Table   Checksum

wenyz.t2    1273189789

...

-rw-r--r-- 1 root root   16384 Aug  4 23:09 0000000000000040.page

-rw-r--r-- 1 root root   98304 Aug  4 23:09 0000000000000041.page /被drop表空间文件

-rw-r--r-- 1 root root   16384 Aug  4 23:09 18446744069414584320.page

count(*)320(行)

Table   Checksum

wenyz.t2    3018070873

....

-rw-r--r-- 1 root root   16384 Aug  4 23:12 0000000000000038.page

-rw-r--r-- 1 root root   32768 Aug  4 23:12 0000000000000039.page

-rw-r--r-- 1 root root   16384 Aug  4 23:12 0000000000000040.page \\这里缺41.page

-rw-r--r-- 1 root root   16384 Aug  4 23:12 18446744069414584320.page

把drop命令在脚本里注释后(还是320行)

以下为精简信息,完整输出信息附后:

#/tmp/init3507.sh

BrI?Zu>o=1uN

mysql: [Warning] Using a password on the command line interface can be insecure.

root@localhost [(none)]>alter user user() identified by 'xxxxx';

Query OK, 0 rows affected (0.00 sec)

root@localhost [(none)]>exit

Bye

mysql: [Warning] Using a password on the command line interface can be insecure.

count(*) ---------------------------------------------------------------------------------320行数据

320

Table   Checksum

wenyz.t2    2368041617

...

-rw-r--r-- 1 root root   32768 Aug  4 23:16 0000000000000039.page

-rw-r--r-- 1 root root   16384 Aug  4 23:16 0000000000000040.page

-rw-r--r-- 1 root root   32768 Aug  4 23:16 0000000000000041.page //320行时不drop是有此表空间文件的

-rw-r--r-- 1 root root   16384 Aug  4 23:16 18446744069414584320.page

[root@db211_23:16:21 /opt/undrop-for-innodb]

#
  • 为了快速测试数据恢复,使用的脚本
    init3507.sh
    /tmp/init3507.sh
pkill mysqld

rm -rf /3507/data/* /3507/logs/*

/usr/local/mysql57/bin/mysqld --defaults-file=/3507/my3507.cnf --initialize-insecure

/usr/local/mysql57/bin/mysqld --defaults-file=/3507/my3507.cnf&

sleep 2

/usr/local/mysql57/bin/mysql -S /tmp/mysql3507.sock -uroot  </tmp/create_t2.sql

rm -rf /opt/undrop-for-innodb/pages-ibdata1

#ls -l

cd /opt/undrop-for-innodb/

sleep 5

rm -rf /opt/undrop-for-innodb/pages-ibdata1

cd /opt/undrop-for-innodb/

/opt/undrop-for-innodb/stream_parser -f /3507/data/ibdata1

ls -l /opt/undrop-for-innodb/pages-ibdata1/FIL_PAGE_INDEX

/tmp/create_t2.sql (由于不能上传sql文件,所以只能改为sh)

alter user user() identified by 'xxxx';

CREATE DATABASE wenyz;

use wenyz;

CREATE TABLE `t2` (

  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,

  `ti` varchar(100) NOT NULL,

  `date` date DEFAULT NULL,

  PRIMARY KEY (`id`)

) ENGINE=InnoDB AUTO_INCREMENT=4079859 DEFAULT CHARSET=utf8;

insert into t2(ti,date) values(substring(MD5(RAND()),floor(RAND()*26)+1,15),now()) ;

insert into t2(ti,date) values(substring(MD5(RAND()),floor(RAND()*26)+1,15),now()) ;

insert into t2(ti,date) values(substring(MD5(RAND()),floor(RAND()*26)+1,15),now()) ;

insert into t2(ti,date) values(substring(MD5(RAND()),floor(RAND()*26)+1,15),now()) ;

insert into t2(ti,date) values(substring(MD5(RAND()),floor(RAND()*26)+1,15),now()) ;

insert into t2(ti,date) values(substring(MD5(RAND()),floor(RAND()*26)+1,15),now()) ;

insert into t2(ti,date) values(substring(MD5(RAND()),floor(RAND()*26)+1,15),now()) ;

insert into t2(ti,date) values(substring(MD5(RAND()),floor(RAND()*26)+1,15),now()) ;

insert into t2(ti,date) values(substring(MD5(RAND()),floor(RAND()*26)+1,15),now()) ;

insert into t2(ti,date) values(substring(MD5(RAND()),floor(RAND()*26)+1,15),now()) ;

insert into t2(ti,date) select ti,date from t2;

insert into t2(ti,date) select ti,date from t2;

insert into t2(ti,date) select ti,date from t2;

insert into t2(ti,date) select ti,date from t2;

insert into t2(ti,date) select ti,date from t2;

select count(*) from t2;

checksum table t2;

drop table t2;

7.参考过的资料 [ Top ]

转自

没有备份怎么恢复被drop的表(利用undrop-for-innodb) - 2森林 - 博客园 https://www.cnblogs.com/2woods/p/9420414.html

MySQL没有备份怎么恢复被drop的表(利用undrop-for-innodb)的更多相关文章

  1. 没有备份怎么恢复被drop的表(利用undrop-for-innodb)

    介绍:     也许大家都难以理解,这么重要的数据为啥不备份(或者备份不可用)?而且还任性的drop table了.显然有备份是最好的,但是它们并不总是可用的.这种情况令人恐惧,但并非毫无希望.在许多 ...

  2. mysql 数据库备份，恢复。。。。

    mysql 数据备份,恢复,恢复没写,这里只写了备份... 先暂作记录吧! 备份:表结构和数据完全分开,默认有一个文件会记录所有表的结构,然后表中数据的备份 如果超过分卷的大小则会分成多个文件,不然则 ...

  3. MySQL的备份和恢复

    MySQL的备份和恢复 备份数据:mysqldump –uroot –p123456 dbname table [option] > dbname.sql mysqldump常用参数option ...

  4. MySQL的备份和恢复-mysqldump

    MySQL的备份和恢复-mysqldump 作者:尹正杰 版权声明:原创作品,谢绝转载!否则将追究法律责任. 一.为什么需要备份 1>.做灾难恢复 天有不测风云嘛,如果你的服务器被黑客攻击了(比 ...

  5. mysql 完整备份和恢复

    mysql 完整备份和恢复   一.MySQL完整备份操作 1.直接打包数据库文件夹 创建数据库auth: MariaDB [(none)]> create database auth;Quer ...

  6. MySQL的备份和恢复-基于LVM快照的备份（lvm-snapshot）

    MySQL的备份和恢复-基于LVM快照的备份(lvm-snapshot) 作者:尹正杰 版权声明:原创作品,谢绝转载!否则将追究法律责任. 一.什么是快照卷 如上图所示,原卷和快照卷可以不一样大,因为 ...

  7. mysql 数据库备份和恢复

    物理备份对比逻辑备份 物理备份是指直接复制包含数据的文件夹和文件.这种类型的备份适用于大数据量且非常重要,遇到问题需要快速回复的数据库. 逻辑备份保存能够代表数据库信息的逻辑结构(CREATE DAT ...

  8. 第九章· MySQL的备份和恢复

    一.备份的原因 运维工作的核心简单概括就两件事: 1)第一个是保护公司的数据. 2)第二个是让网站能7*24小时提供服务(用户体验).  备份的原因 1)备份就是为了恢复. 2)尽量减少数据的丢失( ...

  9. JSP 实现 之 调用java方法实现MySQL数据库备份和恢复

    package cn.qm.db; import java.io.BufferedReader; import java.io.DataInputStream; import java.io.IOEx ...

随机推荐

  1. 剑指Offer_编程题_17

    题目描述 输入两棵二叉树A,B,判断B是不是A的子结构.(ps:我们约定空树不是任意一个树的子结构)   /* struct TreeNode { int val; struct TreeNode * ...

  2. Netsarang

    下载 https://www.netsarang.com/zh/all-downloads/ 建议直接下载 xmanager-power-suite,里面包含了 Xmanager.Xshell.Xft ...

  3. springBootJpa的复杂查询

    分页 /** * 条件查询+分页 * @param whereMap * @param page * @param size * @return */ public Page<CaseManag ...

  4. Linux拉你入门

    前言:为了做一个更优秀的程序猿,Linux是必不可少的,因此利用闲杂的时间来增加自己对Linux的认识 (一)关于Linux命令编(至于怎样安装vmvare这一个章节就先不介绍了) 1.基础命令 1. ...

  5. PHP7 学习笔记（十二）gRPC

    GitHub:https://github.com/grpc/grpc/tree/master/src/php 环境:Linux + php7 1.安装grpc pecl install grpc 编 ...

  6. 深入浅出mybatis之入门使用

    写在前面 mybatis是一个持久层框架,可以支持SQL定制和存储过程,实现数据库记录到Java POJO对象之间的映射. 所以说,mybatis是一个ORM框架. 这个ORM可以通过2种方式实现:x ...

  7. 使用Verilog HDL语言注意事项

    1.wire和reg区别,输入输出是wire型,表示硬件线的连接,要在always模块里被赋值需要中间reg型变量,两者通过: assign 输入/输出=reg型中间变量 2.case的default ...

  8. 【PgSQL安装（含配置）】PostgreSQL简称PgSQL，是1980以加利福尼亚大学开发的DBMS，严格遵守标准SQL。

    [下载地址]http://www.enterprisedb.com/products-services-training/pgdownload#windows …………………………………………………… ...

  9. 20155324王鸣宇安装虚拟机+初次学习Linux的感想20155324

    安装Linux系统 这是最后一次预备作业,但不是最后一次作业.当然要认真对待,在这个除旧迎新的日子里.认真的花了一个下午的时间专研学习了如何安装Linux系统.通过学习了基于VirtualBox虚拟机 ...

  10. 使用Python批量修改文件名

    使用os.rename(fold,newfilename)对文件重命名 # coding:utf-8 import os filename_list = os.listdir('./') for fi ...