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mysql8基礎 邏輯運算 not 非

資料,資料,命根就在資料 ! 操作資料庫時,一定要謹慎小心。師萬物 這裡的程式碼看看就好,要有自己的判斷。遇到抉擇,要不恥上下問。

example

stu@Ubuntu:~$ mysql -u root -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 53
Server version: 8.0.12 MySQL Community Server - GPL

Copyright (c) 2000, 2018, Oracle and/or
its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql> use db_chinese_medicine; Reading table
information for completion of table and column names You can turn off this feature to get a quicker startup with -A Database changed mysql> select * from t_fruit; +----+-----------+-------+--------+----------+------------------------------------+---------------------+---------------------+ | id |
name | count | price | is_sales | note | gmt_create | gmt_modified | +----+-----------+-------+--------+----------+------------------------------------+---------------------+---------------------+ | 1 | 甜瓜 | 10 | 3.210 | 1 || 2018-10-27 19:42:56 | 2018-10-27 19:42:56 | | 2 | 烏梅 | 20 | 5.430 | 1 || 2018-10-27 19:46:21 | 2018-10-27 19:46:21 | | 3 | 櫻桃 | 30 | 6.540 | 1 || 2018-10-27 19:46:48 | 2018-10-27 19:46:48 | | 4 | 甘蔗 | 50 | 7.650 | 0 || 2018-10-27 19:51:13 | 2018-10-27 19:51:13 | | 5 | 菠蘿蜜 | 50 | 8.760 | 1 | 菠蘿蜜和菠蘿是什麼關係? | 2018-10-27 19:55:44 | 2018-10-27 19:55:44 | | 6 | 無花果 | 100 | 8.760 | 1 || 2018-10-27 19:57:48 | 2018-10-27 19:57:48 | | 7 | 山葡萄 | 200 | 5.550 | 1 || 2018-10-27 20:11:07 | 2018-10-27 20:11:07 | | 8 | 無漏子 | 5 | 3.320 | 0 || 2018-10-27 20:11:07 | 2018-10-27 20:11:07 | | 9 | 五斂子 | 12 | 6.010 | 0 || 2018-10-27 20:11:07 | 2018-10-27 20:11:07 | | 10 || 80 | 10.200 | 0 || 2018-10-27 20:11:07 | 2018-10-27 20:11:07 | | 11 || 5 | 3.320 | 0 | NULL | 2018-10-27 20:24:01 | 2018-10-27 20:24:01 | | 12 | 龍眼 | 49 | 6.540 | 0 | NULL | 2018-10-27 20:24:01 | 2018-10-27 20:24:01 | | 13 | 楂子 | 0 | 8.100 | 0 | NULL | 2018-10-27 20:24:01 | 2018-10-27 20:24:01 | +----+-----------+-------+--------+----------+------------------------------------+---------------------+---------------------+ 13 rows in set (0.00 sec) mysql> select * from t_fruit where not(note = '無'); +----+-----------+-------+-------+----------+------------------------------------+---------------------+---------------------+ | id | name | count | price | is_sales | note | gmt_create | gmt_modified | +----+-----------+-------+-------+----------+------------------------------------+---------------------+---------------------+ | 5 | 菠蘿蜜 | 50 | 8.760 | 1 | 菠蘿蜜和菠蘿是什麼關係? | 2018-10-27 19:55:44 | 2018-10-27 19:55:44 | +----+-----------+-------+-------+----------+------------------------------------+---------------------+---------------------+ 1 row in set (0.00 sec) mysql> exit Bye stu@Ubuntu:~$

more knowledge

  • 注意:在note列中有三種資料:無,null,普通評論。
  • where not(note = ‘無’) 語句不但忽略了 無,而且還把 null 也給忽略了!

resource

MySQL是一個關係型資料庫管理系統,目前是開源的(2018-10)。 許可權明確,恰當選擇引擎與字符集,命名簡潔明瞭與規範。 MariaDB,Redis,MongoDB,PostgreSQL,Hive,HBase等,可以簡單地瞭解。 Workbench,phpMyAdmin,Navicat等圖形化管理工具,可以試用一下。