標籤:1單值(Scalar operand)只有當外層(Parent)不為空白時,才返回相應值;否則返回NULL。 note:For the subquery just shown, if t1 were empty, the result would be NULL even though s2 is NOT NULL.2 用於操作符比較[14.2.10.2 Comparisons Using
標籤:原文地址:http://www.linuxbrigade.com/back-up-all-of-your-mysql-databases-nightly/Put the following into something like /usr/local/bin/mysql_backup.sh and since it has MySQL’s root password in it, make sure that you chmod 700 to it so no one
標籤:這個鬼emoji表情是4個位元組,mysql使用的utf8編碼,UTF8佔3個位元組,要儲存那個emoji表情需要將mysql編碼由UFT8改為UFT8的超集,utf8mb4;改資料庫編碼容易引起大面的亂碼災難。所以當遇到emoji字元表情的時候做特殊處理。網上也有很多處理方案,最後找到了一個貼上地址和代碼:https://github.com/BriquzStudio/php-emoji ,多謝class Emoji{/** * Encode emoji in text * @
標籤:mysql下面是常用mysql資料庫查詢總結:顯示一個資料表的所有資料。mysql> SELECT * FROM [table name];返回指定資料表的各列資訊。mysql> show columns from [table name];使用值“blog”過濾顯示選定的某些行。mysql> SELECT * FROM [table name] WHERE user = "blog";顯示所有包含name為”Bob”和phone
標籤:mysql查看儲存引擎:mysql> show engines;查看innodb引擎有關所有變數:mysql> show VARIABLES LIKE "%innodb%";mysql> SHOW VARIABLES;設定每個表獨立使用一個資料表空間[[email protected] ~]# echo "innodb_file_per_table = 1" >>/etc/my.cnf重啟生效:[[email protected] ~]#
標籤:mysql本機存取權限:mysql> GRANT ALL PRIVILEGES ON *.* TO ‘username‘@‘localhost‘ IDENTIFIED BY ‘password‘;遠端存取許可權:mysql> GRANT ALL PRIVILEGES ON *.* TO ‘username‘@‘%‘ IDENTIFIED BY ‘password‘;FLUSH PRIVILEGES;增加使用者 test1 密碼