(1, '张三', 95) ON DUPLICATE KEY UPDATE score = 95; -- 从其他表插入数据 INSERT INTO students_backup SELECT * FROM students WHERE class = '计算机科学1班'; -- 忽略错误继续执行 INSERT IGNORE INTO students (id, name, age) VALUES (1, '张三', 20); 实际应用场景当新学生入学时,需要将...
grant select,insert,update,delete on mydb.* to [email=test2@localhost]test2@localhost[/email] identified by “abc”; 如果你不想test2有密码,可以再打一个命令将密码消掉。 grant select,insert,update,delete on mydb.* to [email=test2@localhost]test2@localhost[/email] identified by “”; 4、数据...
mysql> SHOW CHARACTER SET;//查看支持的所有字符集 1字符集用来定义输入的内容的 支持41种2mysql> show characterset;3+---+---+---+---+4| Charset | Description | Default collation | Maxlen |5+---+---+---+---+6| big5 | Big5 Traditional Chinese | big5_chinese_ci |2|7| dec8 | ...
SELECT employee_id,last_name,department_name FROM employees e JOIN departments d USING (department_id); 你能看出与自然连接 NATURAL JOIN 不同的是,USING 指定了具体的相同的字段名称,你需要在 USING 的括号 () 中填入要指定的同名字段。同时使用 JOIN...USING 可以简化 JOIN ON 的等值连接。它与下 面...
selectdate_format(now() ,'%Y%m%d')as datetime ; mysql字符集在选择字符集是 _ci 大小写不敏感 _cs 大小写敏感 _bin 二进制 字符集(Charset):是一个系统支持的所有抽象字符的集合。字符是各种文字和符号的总称,包括各国家文字、标点符号、图形符号、数字等。
CHARACTER_LENGTH()是CHAR_LENGTH()的同义词。 COMPRESS(string_to_compress) 压缩一个字符串。这个函数要求 MySQL已经用一个诸如zlib的压缩库压缩过。 否则,返回值始终是NULL。UNCOMPRESS() 可将压缩过的字符串进行解压缩。 mysql>SELECT LENGTH(COMPRESS(REPEAT('a',1000))); ...
SELECT YEAR(CURDATE()),MONTH(CURDATE()),DAY(CURDATE()), HOUR(CURTIME()),MINUTE(NOW()),SECOND(SYSDATE()) FROM DUAL; SELECT MONTHNAME('2021-10-26'),DAYNAME('2021-10-26'),WEEKDAY('2021-10-26'), QUARTER(CURDATE()),WEEK(CURDATE()),DAYOFYEAR(NOW()), DAYOFMONTH(NOW()),DAYOFWEEK(...
ERROR 1300 (HY000): Invalid utf8 character string ” AI检测代码解析 load data infile 'f:/Mysql/data/song.sql' into table music character set utf8 fields terminated by "|||" (mid,name,sid,album); 1. 2. 3. 4. 5. 不管terminated by换成什么都会出现这个错误,然后百度了一下说需要改表的...
The simplest form of .query() is .query(sqlString, callback), where a SQL string is the first argument and the second is a callback: connection.query('SELECT * FROM `books` WHERE `author` = "David"', function (error, results, fields) { // error will be an Error if one occurred...
3.Select the code which shows the countries that end in A or L 4.Pick the result from the query SELECT name,length(name) FROM world WHERE length(name)=5 and continent='Europe' 5.Here are the first few rows of the world table: ...