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Legal Studies带 OR 和 AND 条件的 MySQL 查询
我们首先创建一个表格 -
mysql> create table DemoTable -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> Name varchar(20), -> Age int -> ); Query OK, 0 rows affected (0.63 sec)
使用 insert 命令在表格中插入一些记录 -
mysql> insert into DemoTable(Name,Age) values('John',21);
Query OK, 1 row affected (0.16 sec)
mysql> insert into DemoTable(Name,Age) values(Null,20);
Query OK, 1 row affected (0.12 sec)
mysql> insert into DemoTable(Name,Age) values('David',23);
Query OK, 1 row affected (0.16 sec)
mysql> insert into DemoTable(Name,Age) values('Carol',null);
Query OK, 1 row affected (0.17 sec)使用 select 语句显示表格中的所有记录 -
mysql> select *from DemoTable;
输出
+----+-------+------+ | Id | Name | Age | +----+-------+------+ | 1 | John | 21 | | 2 | NULL | 20 | | 3 | David | 23 | | 4 | Carol | NULL | +----+-------+------+ 4 rows in set (0.00 sec)
以下是带 OR 和 AND 条件的查询 -
mysql> select *from DemoTable -> where Name='David' OR (Name is null AND Age=20);
输出
+----+-------+------+ | Id | Name | Age | +----+-------+------+ | 2 | NULL | 20 | | 3 | David | 23 | +----+-------+------+ 2 rows in set (0.00 sec)
更新于：2019 年 7 月 30 日
132 次浏览
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