mysql中的sql_mode模式例項詳解
本文例項講述了mysql中的sql_mode模式。分享給大家供大家參考,具體如下:
mysql資料庫的中有一個環境變數sql_mode,定義了mysql應該支援的sql語法,資料校驗等!我們可以通過以下方式檢視當前資料庫使用的sql_mode:
mysql> select @@sql_mode; +----------------------------------------------------------------+ | @@sql_mode | +----------------------------------------------------------------+ | STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION | +----------------------------------------------------------------+
mysql5.0以上版本支援三種sql_mode模式
ANSI模式 |
寬鬆模式,對插入資料進行校驗,如果不符合定義型別或長度,對資料型別調整或截斷儲存,報warning警告。 |
TRADITIONAL模式 |
嚴格模式,當向mysql資料庫插入資料時,進行資料的嚴格校驗,保證錯誤資料不能插入,報error錯誤。用於事物時,會進行事物的回滾。 |
STRICT_TRANS_TABLES模式 |
嚴格模式,進行資料的嚴格校驗,錯誤資料不能插入,報error錯誤。 |
1 ANSI模式
在ANSI模式下,當我們插入資料時,未滿足列長度要求時,資料同樣會插入成功,但是對超出列長度的欄位進行截斷,同時報告warning警告。
mysql> set @@sql_mode=ANSI; Query OK,0 rows affected (0.00 sec) mysql> create table test(name varchar(4),pass varchar(4)); Query OK,0 rows affected (0.03 sec) mysql> insert into test values('aaaaa','aaaaa'),('bbbb','bbbb'); Query OK,2 rows affected,2 warnings (0.02 sec) Records: 2 Duplicates: 0 Warnings: 2 mysql> show warnings; +---------+------+-------------------------------------------+ | Level | Code | Message | +---------+------+-------------------------------------------+ | Warning | 1265 | Data truncated for column 'name' at row 1 | | Warning | 1265 | Data truncated for column 'pass' at row 1 | +---------+------+-------------------------------------------+ 2 rows in set (0.00 sec) mysql> select * from test; +------+------+ | name | pass | +------+------+ | aaaa | aaaa | | bbbb | bbbb | +------+------+ 2 rows in set (0.00 sec)
2 STRICT_TRANS_TABLES模式
在STRICT_TRANS_TABLES模式下,當我們插入資料時,mysql會嚴格的進行資料的校驗,當發現插入列值未滿足要求,直接報告error錯誤,保證了錯誤資料無法插入到資料庫中。
mysql> set @@sql_mode=STRICT_TRANS_TABLES; Query OK,0 rows affected (0.02 sec) mysql> insert into test values('aaaaa','bbbb'); ERROR 1406 (22001): Data too long for column 'name' at row 1 mysql> show errors; +-------+------+------------------------------------------+ | Level | Code | Message | +-------+------+------------------------------------------+ | Error | 1406 | Data too long for column 'name' at row 1 | +-------+------+------------------------------------------+ 1 row in set (0.00 sec) mysql> select * from test; Empty set (0.00 sec)
3 TRADITIONAL模式,初看結果是不是一樣
mysql> set @@sql_mode=TRADITIONAL; Query OK,'bbbb'); ERROR 1406 (22001): Data too long for column 'name' at row 1 mysql> show errors; +-------+------+------------------------------------------+ | Level | Code | Message | +-------+------+------------------------------------------+ | Error | 1406 | Data too long for column 'name' at row 1 | +-------+------+------------------------------------------+ 1 row in set (0.00 sec) mysql> select * from test; Empty set (0.00 sec)
但是,可以看看設定後的情況
mysql> set @@sql_mode=TRADITIONAL; Query OK,0 rows affected (0.00 sec) mysql> select @@sql_mode\G *************************** 1. row *************************** @@sql_mode: STRICT_TRANS_TABLES,STRICT_ALL_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,TRADITIONAL,NO_ENGINE_SUBSTITUTION 1 row in set (0.00 sec)
在TRADITIONAL模式下,對所有的事務儲存引擎,非事務儲存引擎檢查,日期型別中的月和日部分不能包含0,不能有0這樣的日期(0000-00-00),資料不能除0,禁止grant自動建立新使用者等一些校驗。
最後:
set @@只是在sessions級別設定的,要想所有的都生效,還是要設定配置檔案
vi /etc/my.cnf
在[mysqld]下面新增如下列:
sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES
#NO_ENGINE_SUBSTITUTION對於不存在的引擎就報錯,不加的話,指定不支援的引擎時指定預設的innodb
另外:sql_mode還有一個配置ONLY_FULL_GROUP_BY,這個表示採用group by帥選資料的時候只能檢視新組內資訊
改模式之前的操作
mysql> select * from employee group by post; +----+--------+--------+-----+------------+-----------------------------------------+--------------+------------+--------+-----------+ | id | name | sex | age | hire_date | post | post_comment | salary | office | depart_id | +----+--------+--------+-----+------------+-----------------------------------------+--------------+------------+--------+-----------+ | 14 | 張野 | male | 28 | 2016-03-11 | operation | NULL | 10000.13 | 403 | 3 | | 9 | 歪歪 | female | 48 | 2015-03-11 | sale | NULL | 3000.13 | 402 | 2 | | 2 | alex | male | 78 | 2015-03-02 | teacher | NULL | 1000000.31 | 401 | 1 | | 1 | egon | male | 18 | 2017-03-01 | 老男孩駐沙河辦事處外交大使 | NULL | 7300.33 | 401 | 1 | +----+--------+--------+-----+------------+-----------------------------------------+--------------+------------+--------+-----------+ 4 rows in set (0.00 sec)
此時的sql_mode:
mysql> select @@sql_mode; +----------------------------------------------------------------+ | @@sql_mode | +----------------------------------------------------------------+ | STRICT_TRANS_TABLES,NO_ENGINE_SUBSTITUTION | +----------------------------------------------------------------+ 1 row in set (0.00 sec)
修改一下,退出再進入才會生效
mysql> set global sql_mode='STRICT_TRANS_TABLES,NO_ENGINE_SUBSTITUTION,ONLY_FULL_GROUP_BY'; Query OK,0 rows affected (0.00 sec) mysql> select @@sql_mode; +----------------------------------------------------------------+ | @@sql_mode | +----------------------------------------------------------------+ | STRICT_TRANS_TABLES,NO_ENGINE_SUBSTITUTION | +----------------------------------------------------------------+ 1 row in set (0.00 sec) mysql> exit Bye
再次進入
mysql> select @@sql_mode; +-----------------------------------------------------------------------------------+ | @@sql_mode | +-----------------------------------------------------------------------------------+ | ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ENGINE_SUBSTITUTION | +-----------------------------------------------------------------------------------+ 1 row in set (0.00 sec)
下面檢視修改後的檢視結果
mysql> select * from employee group by post; //只能檢視post ERROR 1055 (42000): 't1.employee.id' isn't in GROUP BY mysql> select post from employee group by post; +-----------------------------------------+ | post | +-----------------------------------------+ | operation | | sale | | teacher | | 老男孩駐沙河辦事處外交大使 | +-----------------------------------------+ 4 rows in set (0.00 sec) mysql> select id,post from employee group by post; ERROR 1055 (42000): 't1.employee.id' isn't in GROUP BY mysql> select name,post from employee group by post,name; //根據group by 後面的選擇檢視 +------------+-----------------------------------------+ | name | post | +------------+-----------------------------------------+ | 張野 | operation | | 程咬金 | operation | | 程咬鐵 | operation | | 程咬銅 | operation | | 程咬銀 | operation | | 丁丁 | sale | | 丫丫 | sale | | 星星 | sale | | 格格 | sale | | 歪歪 | sale | | alex | teacher | | jingliyang | teacher | | jinxin | teacher | | liwenzhou | teacher | | wupeiqi | teacher | | xiaomage | teacher | | yuanhao | teacher | | egon | 老男孩駐沙河辦事處外交大使 | +------------+-----------------------------------------+ 18 rows in set (0.00 sec)
更多關於MySQL相關內容感興趣的讀者可檢視本站專題:《MySQL查詢技巧大全》、《MySQL常用函式大彙總》、《MySQL日誌操作技巧大全》、《MySQL事務操作技巧彙總》、《MySQL儲存過程技巧大全》及《MySQL資料庫鎖相關技巧彙總》
希望本文所述對大家MySQL資料庫計有所幫助。