MySQL id, datetime, charset

Author: LinWanCen

db/DB_table.md

@@ -27,4 +27,11 @@ import javax.validation.constraints.NotNull;
 
 ### 表前加库名可以方便后人接手
 
-虽然可以在`information_schema.TABLES`查
+虽然可以在`information_schema.TABLES`查
+
+
+### datetime(6) 用最 6 位小数或和 java 一样 3 位小数，否则默认没有小数
+
+### 创建时间和更新时间使用数据库自动生生成避免程序与数据库时钟差，创建与更新时不要写这两个字段
+
+### 除非数据量较小时不用 id，否则 InnoDB 用 id 当主键以提升 B+ 树存储效率

db/MySQL_charset.md

@@ -15,11 +15,11 @@ show variables like 'collation%';
 vim /etc/mysql/my.cnf
 
 [client]
-default-character-set=utf8mb4_bin
+default-character-set=utf8mb4
 
 [mysqld]
 default-storage-engine=INNODB
-character-set-server=utf8mb4_bin
+character-set-server=utf8mb4
 collation-server=utf8mb4_bin
 
 /etc/init.d/mysql stop
@@ -28,42 +28,50 @@ collation-server=utf8mb4_bin
 
 ```mysql
 -- 服务端
-set global character_set_server=utf8mb4_bin;
-set global character_set_database=utf8mb4_bin;
+set global character_set_server = utf8mb4;
+set global character_set_database = utf8mb4;
 
 -- 客户端
-set global character_set_client=utf8mb4_bin;
-set global character_set_connection=utf8mb4_bin;
-set global character_set_results=utf8mb4_bin;
+set global character_set_client = utf8mb4;
+set global character_set_connection = utf8mb4;
+set global character_set_results = utf8mb4;
 
-create database if not exists `db1` /*!40100 default character set utf8mb4_bin */;
+create database if not exists `db1` /*!40100 default character set utf8mb4 */;
 
--- drop table if exists `db1_table1`;
-create table if not exists db1_table1
+-- show create table db1_table0;
+drop table if exists `db1_table0`;
+create table if not exists db1_table0
 (
-  id          bigint unsigned auto_increment comment '自增主键',
-  create_time datetime not null              comment '创建时间',
-  update_time datetime null                  comment '更新时间',
-  constraint db1_table1_pk primary key (id),
-  constraint db1_table1_id_unique_index unique (id)
+    id          bigint(20) unsigned not null auto_increment comment '自增主键',
+    create_time datetime(6)         not null default current_timestamp(6) comment '创建时间',
+    update_time datetime(6)         not null default current_timestamp(6) on update current_timestamp(6) comment '更新时间',
+    constraint db1_table1_pk primary key (id),
+    constraint db1_table1_id_unique_index unique (id)
 ) engine = InnoDB
-  default charset = utf8mb4_bin comment ='表名';
+  default charset = utf8mb4
+  collate = utf8mb4_bin comment ='表名';
 
--- 主键用id
+-- show create table db1_table1;
+drop table if exists `db1_table1`;
 create table if not exists db1_table1
 (
-  id          bigint unsigned auto_increment primary key unique comment '自增主键',
-  create_time datetime not null comment '创建时间',
-  update_time datetime null comment '更新时间'
-) ENGINE = InnoDB
-  DEFAULT CHARSET = utf8mb4_bin COMMENT ='表名';
+    id          bigint(20) unsigned not null auto_increment primary key unique comment '自增主键',
+    create_time datetime(6)         not null default current_timestamp(6) comment '创建时间',
+    update_time datetime(6)         not null default current_timestamp(6) on update current_timestamp(6) comment '更新时间'
+) engine = InnoDB
+  default charset = utf8mb4
+  collate = utf8mb4_bin comment ='表名';
 
--- show create table db1_table1;
-CREATE TABLE `db1_table1` (
-  `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT COMMENT '自增主键',
-  `create_time` datetime NOT NULL COMMENT '创建时间',
-  `update_time` datetime DEFAULT NULL COMMENT '更新时间',
-  PRIMARY KEY (`id`),
-  UNIQUE KEY `id` (`id`)
-) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4_bin COMMENT='表名'
+-- show create table db1_table2;
+drop table if exists `db1_table2`;
+create table if not exists `db1_table2`
+(
+    `id`          bigint(20) unsigned not null auto_increment comment '自增序号',
+    `create_time` datetime(6)         not null default current_timestamp(6) comment '创建时间',
+    `update_time` datetime(6)         not null default current_timestamp(6) on update current_timestamp(6) comment '更新时间',
+    primary key (`id`),
+    unique key `id` (`id`)
+) engine = InnoDB
+  default charset = utf8mb4
+  collate = utf8mb4_bin comment ='表名';
 ```

db/SQL.md

@@ -18,8 +18,8 @@
 
 ```sh
 # -v 显示日志 -U 禁止无 where 更新
-mysql -v -U -uroot -proot -h $IP -P 3306 --default-character-set=utf8mb4_bin < mysql_run.sql
-set character set utf8mb4_bin;
+mysql -v -U -uroot -proot -h $IP -P 3306 --default-character-set=utf8mb4 < mysql_run.sql
+set character set utf8mb4;
 
 # 避免 Oracle 乱码
 export NLS_LANG="AMERICAN_AMERICA.AL32UTF8"

db/comment/MySQL_comment.sql

@@ -1,10 +1,14 @@
 -- 创建时添加注释
-CREATE TABLE `COMMON_SEQ`
+CREATE TABLE `db1_table0`
 (
-    `APP_CODE` char(6) NOT NULL COMMENT '应用编码',
-    UNIQUE KEY `COMMON_SEQ_APP_CODE_uindex` (`APP_CODE`)
+    `id`          bigint unsigned NOT NULL AUTO_INCREMENT COMMENT '自增主键',
+    `create_time` datetime(6)     NOT NULL DEFAULT CURRENT_TIMESTAMP(6) COMMENT '创建时间',
+    `update_time` datetime(6)     NOT NULL DEFAULT CURRENT_TIMESTAMP(6) ON UPDATE CURRENT_TIMESTAMP(6) COMMENT '更新时间',
+    PRIMARY KEY (`id`),
+    UNIQUE KEY `db1_table1_id_unique_index` (`id`)
 ) ENGINE = InnoDB
-  DEFAULT CHARSET = utf8mb4_bin COMMENT ='流水号表';
+  DEFAULT CHARSET = utf8mb4
+  COLLATE = utf8mb4_bin COMMENT ='表名';
 
 -- 添加表注释
 ALTER TABLE COMMON_SEQ COMMENT '流水号表';
@@ -30,7 +34,7 @@ WHERE TABLE_SCHEMA not in ('information_schema', 'performance_schema', 'mysql',
 # 查询列在哪个表与注释
 SELECT c.TABLE_SCHEMA, c.TABLE_NAME, t.TABLE_COMMENT, COLUMN_NAME, COLUMN_COMMENT, COLUMN_TYPE, IS_NULLABLE
 FROM information_schema.COLUMNS c JOIN information_schema.TABLES t ON t.TABLE_NAME = c.TABLE_NAME  AND t.TABLE_SCHEMA = c.TABLE_SCHEMA WHERE 1=1
-# AND TABLE_SCHEMA = '数据库名'
- AND TABLE_NAME = '表名'
+# AND c.TABLE_SCHEMA = '数据库名'
+ AND c.TABLE_NAME = '表名'
 # AND c.COLUMN_NAME = '列名'
 # AND c.COLUMN_COMMENT = '列注释'

db/comment/MySQL_comment_column.sh

@@ -1,7 +1,7 @@
 echo '<style> table {border-collapse: collapse;}  th, td {border: 1px solid lightgray;padding-left: 5px;padding-right: 5px;}</style><table>' >\
 APP_NAME-not_comment_column.html
 
-mysql -h ___IP___ -P 3306 -u 用户名 -p 密码 --default-character-set=utf8mb4_bin -e \
+mysql -h ___IP___ -P 3306 -u 用户名 -p 密码 --default-character-set=utf8mb4 -e \
 "SELECT TABLE_SCHEMA, TABLE_NAME, COLUMN_NAME, COLUMN_COMMENT FROM information_schema.COLUMNS WHERE TABLE_SCHEMA not in ('information_schema','performance_schema','mysql','sys') AND COLUMN_COMMENT = '';"\
 | sed 's/\t/<\/td><td>/g; s/^/<tr><td>/; s/$/<\/td><\/tr>/;' >>\
 APP_NAME-not_comment_column.html

db/comment/MySQL_comment_table.sh

@@ -1,7 +1,7 @@
 echo '<style> table {border-collapse: collapse;}  th, td {border: 1px solid lightgray;padding-left: 5px;padding-right: 5px;}</style><table>' >\
 APP_NAME-not_comment_table.html
 
-mysql -h ___IP___ -P 3306 -u 用户名 -p 密码 --default-character-set=utf8mb4_bin -e \
+mysql -h ___IP___ -P 3306 -u 用户名 -p 密码 --default-character-set=utf8mb4 -e \
 "SELECT TABLE_SCHEMA, TABLE_NAME, TABLE_COMMENT FROM information_schema.TABLES WHERE TABLE_SCHEMA not in ('information_schema','performance_schema','mysql','sys') AND TABLE_COMMENT = '';"\
 | sed 's/\t/<\/td><td>/g; s/^/<tr><td>/; s/$/<\/td><\/tr>/;' >>\
 APP_NAME-not_comment_table.html

db/sql_sh/loop_run.sh

@@ -42,7 +42,7 @@ do
       echo \#\#\# start ${USER_arr[$i]}/***@$IP:1521/ORCL @oracle_run.sql
 #      sqlplus ${USER_arr[$i]}/${PASS_arr[$i]}@$IP:1521/ORCL @oracle_run.sql
         # -v 显示日志 -U 禁止无 where 更新
-#        mysql -v -U -u${USER_arr[$i]} -p${PASS_arr[$i]} -h $IP -P 3306 --default-character-set=utf8mb4_bin < mysql_run.sql
+#        mysql -v -U -u${USER_arr[$i]} -p${PASS_arr[$i]} -h $IP -P 3306 --default-character-set=utf8mb4 < mysql_run.sql
       echo \#\#\# end ${USER_arr[$i]}/***@$IP:1521/ORCL @oracle_run.sql
       cd ..
     done

db/sql_sh/mysql_run.sql

@@ -1,4 +1,4 @@
-set character set utf8mb4_bin;
+set character set utf8mb4;
 source /home/admin/db/appName/create_table.sql;
 source /home/admin/db/appName/insert_data.sql;
 source /home/admin/db/appName/update_data.sql;