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是的，NOT EQUAL 在 MySQL 中存在于 運算符的形式中。語法如下 –

SELECT * FROM yourTableName WHERE yourColumnName <> yourValue;

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為了理解上述語法，讓我們創建一個表。創建表的查詢如下 –

mysql> create table DoesNotEqualDemo
   -> (
   -> Id int NOT NULL AUTO_INCREMENT,
   -> Name varchar(20),
   -> PRIMARY KEY(Id)
   -> );
Query OK, 0 rows affected (0.98 sec)

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使用插入命令在表中插入一些記錄。插入記錄的查詢如下 –

mysql> insert into DoesNotEqualDemo(Name) values(NULL);
Query OK, 1 row affected (0.24 sec)

mysql> insert into DoesNotEqualDemo(Name) values('John');
Query OK, 1 row affected (0.18 sec)

mysql> insert into DoesNotEqualDemo(Name) values('Carol');
Query OK, 1 row affected (0.43 sec)

mysql> insert into DoesNotEqualDemo(Name) values('Bob');
Query OK, 1 row affected (0.13 sec)

mysql> insert into DoesNotEqualDemo(Name) values('');
Query OK, 1 row affected (0.13 sec)

mysql> insert into DoesNotEqualDemo(Name) values('Larry');
Query OK, 1 row affected (0.13 sec)

mysql> insert into DoesNotEqualDemo(Name) values(NULL);
Query OK, 1 row affected (0.10 sec)

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使用 select 語句顯示表中的所有記錄。查詢如下 –

mysql> select *from DoesNotEqualDemo;

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以下是輸出 –

+----+-------+
| Id | Name  |
+----+-------+
|  1 | NULL  |
|  2 | John  |
|  3 | Carol |
|  4 | Bob   |
|  5 |       |
|  6 | Larry |
|  7 | NULL  |
+----+-------+
7 rows in set (0.00 sec)

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這里是選擇所有不等于 NULL 以及空字符串的記錄的查詢 –

mysql> select *from DoesNotEqualDemo where Name <> 'NULL' and Name <> '';

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以下是輸出 –

+----+-------+
| Id | Name  |
+----+-------+
|  2 | John  |
|  3 | Carol |
|  4 | Bob   |
|  6 | Larry |
+----+-------+
4 rows in set (0.00 sec)

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以上就是MySQL 中不存在 NOT EQUAL 嗎？的詳細內容，更多請關注www.92cms.cn其它相關文章！