MySQL 열에 문자열이 나타나는 횟수를 확인하시겠습니까?

먼저 테이블을 생성하겠습니다 -

mysql> create table DemoTable704 (SubjectName text);
Query OK, 0 rows affected (0.58 sec)

삽입 명령을 사용하여 테이블에 일부 레코드 삽입 -

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)

select 문을 사용하여 테이블의 모든 레코드 표시 -

mysql> select *from DemoTable704;

그러면 다음과 같은 출력이 생성됩니다. -

+--------------------------------------+
| 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)

다음은 열에 문자열이 몇 번 나타나는지 계산하는 쿼리입니다 -

mysql> SELECT COUNT(*) from DemoTable704 WHERE SubjectName LIKE '%Introduction to MySQL%';

그러면 다음과 같은 출력이 생성됩니다. -

+----------+
| COUNT(*) |
+----------+
| 3        |
+----------+
1 row in set (0.00 sec)