How to find string count of a particular id in a column using a MySQL query?

For this, use the CHAR_LENGTH() function in MySQL. Let us first create a table −

mysql> create table DemoTable
   (
   Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,
   Subject longtext
   );
Query OK, 0 rows affected (1.17 sec)

Now you can insert some records in the table using insert command −

<span class="pln">mysql</span><span class="pun">></span><span class="pln"> insert </span><span class="kwd">into</span><span class="pln"> </span><span class="typ">DemoTable</span><span class="pun">(</span><span class="typ">Subject</span><span class="pun">)</span><span class="pln"> values</span><span class="pun">(</span><span class="str">'MySQL,MongoDB'</span><span class="pun">);</span>
<span class="typ">Query</span><span class="pln"> OK</span><span class="pun">,</span><span class="pln"> </span><span class="lit">1</span><span class="pln"> row affected </span><span class="pun">(</span><span class="lit">0.20</span><span class="pln"> sec</span><span class="pun">)</span>
<span class="pln">mysql</span><span class="pun">></span><span class="pln"> insert </span><span class="kwd">into</span><span class="pln"> </span><span class="typ">DemoTable</span><span class="pun">(</span><span class="typ">Subject</span><span class="pun">)</span><span class="pln"> values</span><span class="pun">(</span><span class="str">'MySQL,MongoDB'</span><span class="pun">);</span>
<span class="typ">Query</span><span class="pln"> OK</span><span class="pun">,</span><span class="pln"> </span><span class="lit">1</span><span class="pln"> row affected </span><span class="pun">(</span><span class="lit">0.17</span><span class="pln"> sec</span><span class="pun">)</span>
<span class="pln">mysql</span><span class="pun">></span><span class="pln"> insert </span><span class="kwd">into</span><span class="pln"> </span><span class="typ">DemoTable</span><span class="pun">(</span><span class="typ">Subject</span><span class="pun">)</span><span class="pln"> values</span><span class="pun">(</span><span class="str">'MongoDB'</span><span class="pun">);</span>
<span class="typ">Query</span><span class="pln"> OK</span><span class="pun">,</span><span class="pln"> </span><span class="lit">1</span><span class="pln"> row affected </span><span class="pun">(</span><span class="lit">0.13</span><span class="pln"> sec</span><span class="pun">)</span>
<span class="pln">mysql</span><span class="pun">></span><span class="pln"> insert </span><span class="kwd">into</span><span class="pln"> </span><span class="typ">DemoTable</span><span class="pun">(</span><span class="typ">Subject</span><span class="pun">)</span><span class="pln"> values</span><span class="pun">(</span><span class="str">'MySQL'</span><span class="pun">);</span>
<span class="typ">Query</span><span class="pln"> OK</span><span class="pun">,</span><span class="pln"> </span><span class="lit">1</span><span class="pln"> row affected </span><span class="pun">(</span><span class="lit">0.15</span><span class="pln"> sec</span><span class="pun">)</span>
<span class="typ">Display</span><span class="pln"> all records </span><span class="kwd">from</span><span class="pln"> the table </span><span class="kwd">using</span><span class="pln"> </span><span class="kwd">select</span><span class="pln"> statement </span><span class="pun">:</span>
<span class="pln">mysql</span><span class="pun">></span><span class="pln"> </span><span class="kwd">select</span><span class="pln"> </span><span class="pun">*</span><span class="kwd">from</span><span class="pln"> </span><span class="typ">DemoTable</span><span class="pun">;</span>

Output

+----+---------------+
| Id | Subject       |
+----+---------------+
| 1  | MySQL,MongoDB |
| 2  | MySQL,MongoDB |
| 3  | MongoDB       |
| 4  | MySQL         |
+----+---------------+
4 rows in set (0.00 sec)

Following is the query to find string count with a MySQL query of a particular id in a column. We are checking for id 1 here −

<span class="pln">mysql</span><span class="pun">></span><span class="pln"> </span><span class="kwd">select</span><span class="pln"> </span><span class="typ">Id</span><span class="pun">,</span><span class="pln">char_length</span><span class="pun">(</span><span class="typ">Subject</span><span class="pun">)</span><span class="pln"> </span><span class="pun">-</span><span class="pln"> char_length</span><span class="pun">(</span><span class="pln">REPLACE</span><span class="pun">((</span><span class="typ">Subject</span><span class="pun">),</span><span class="pln"> </span><span class="str">','</span><span class="pun">,</span><span class="pln"> </span><span class="str">''</span><span class="pun">))+</span><span class="lit">1</span><span class="pln"> </span>
<span class="pln">   AS </span><span class="typ">FreqSubject </span><span class="kwd">from</span><span class="pln"> </span><span class="typ">DemoTable </span><span class="pln">WHERE char_length</span><span class="pun">(</span><span class="typ">Subject</span><span class="pun">)</span><span class="pln"> </span><span class="pun">></span><span class="pln"> </span><span class="lit">0</span><span class="pln"> AND </span><span class="typ">Id</span><span class="pln"> </span><span class="pun">=</span><span class="pln"> </span><span class="lit">1</span><span class="pun">;</span>

Output

+----+-------------+
| Id | FreqSubject |
+----+-------------+
| 1  | 2           |
+----+-------------+
1 row in set (0.02 sec)