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法律研究获取字符串在 MySQL 列中出现的次数
我们首先创建一个表 -
mysql> create table DemoTable704 (SubjectName text); Query OK, 0 rows affected (0.58 sec)
使用 insert 命令插入一些记录 -
mysql> insert into DemoTable704 values('Introduction to MySQL');
Query OK, 1 row affected (0.15 sec)
mysql> insert into DemoTable704 values('Introduction to MongoDB');
Query OK, 1 row affected (0.17 sec)
mysql> insert into DemoTable704 values('Introduction to MySQL');
Query OK, 1 row affected (0.31 sec)
mysql> insert into DemoTable704 values('Introduction to Java');
Query OK, 1 row affected (0.39 sec)
mysql> insert into DemoTable704 values('Introduction to MongoDB');
Query OK, 1 row affected (0.14 sec)
mysql> insert into DemoTable704 values('Introduction to MySQL');
Query OK, 1 row affected (0.13 sec)
mysql> insert into DemoTable704 values('Introduction to C');
Query OK, 1 row affected (0.08 sec)
mysql> insert into DemoTable704 values('Introduction to Spring and Hibernate');
Query OK, 1 row affected (0.12 sec)使用 select 语句显示表中的所有记录 -
mysql> select *from DemoTable704;
这将产生以下输出 -
+--------------------------------------+ | SubjectName | +--------------------------------------+ | Introduction to MySQL | | Introduction to MongoDB | | Introduction to MySQL | | Introduction to Java | | Introduction to MongoDB | | Introduction to MySQL | | Introduction to C | | Introduction to Spring and Hibernate | +--------------------------------------+ 8 rows in set (0.00 sec)
以下是对字符串在列中出现的次数进行计数的查询 -
mysql> SELECT COUNT(*) from DemoTable704 WHERE SubjectName LIKE '%Introduction to MySQL%';
这将产生以下输出 -
+----------+ | COUNT(*) | +----------+ | 3 | +----------+ 1 row in set (0.00 sec)
更新于：21-Aug-2019
309 次浏览
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