在MySQL中选择WHERE IN null吗？
以下是语法-
select yourColumnName1, yourColumnName2, yourColumnName3, . . . N from yourTableName where yourValue in(yourColumnName1,yourColumnName2) or yourColumnName1 is NULL;
让我们创建一个表-
mysql> create table demo60 −> ( −> id int not null auto_increment primary key, −> first_name varchar(20), −> last_name varchar(20) −> ) −> ;
借助insert命令将一些记录插入表中-
mysql> insert into demo60(first_name,last_name) values('John','Smith');
mysql> insert into demo60(first_name,last_name) values('John','Doe');
mysql> insert into demo60(first_name,last_name) values(null,'Brown');
mysql> insert into demo60(first_name,last_name) values('David','Miller');
mysql> insert into demo60(first_name,last_name) values('David','Smith');
mysql> insert into demo60(first_name,last_name) values('Chris','Brown');使用select语句显示表中的记录-
mysql> select *from demo60;
这将产生以下输出-
+----+------------+-----------+ | id | first_name | last_name | +----+------------+-----------+ | 1 | John | Smith | | 2 | John | Doe | | 3 | NULL | Brown | | 4 | David | Miller | | 5 | David | Smith | | 6 | Chris | Brown | +----+------------+-----------+ 6 rows in set (0.00 sec)
以下是选择NULL的查询-
Mysql> select −> id, −> first_name, −> last_name −> from demo60 −> where 'John' in(first_name,last_name) or first_name is NULL;
这将产生以下输出-
+----+------------+-----------+ | id | first_name | last_name | +----+------------+-----------+ | 1 | John | Smith | | 2 | John | Doe | | 3 | NULL | Brown | +----+------------+-----------+ 3 rows in set (0.00 sec)
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