MySQL SQL determines whether a string exists in another string

MySQL Tutorial SQL determines whether a string exists in another string

Locate (Substr,str,pos)

Returns the substring substr the first occurrence of the string str, if SUBSTR is not inside STR, returns 0.

Mysql> Select locate (' Bar ', ' Foobarbar ');
-> 4
Mysql> Select locate (' Xbar ', ' foobar ');
-> 0

Locate (Substr,str,pos)
Returns the substring substr the position of the first occurrence of the string str, starting at the location POS. If SUBSTR is not inside STR, return 0.

Mysql> Select locate (' Bar ', ' Foobarbar ', 5);
-> 7

Take a look at the example below
*/

$cityid = 11;
$sql = "SELECT * from Tbname where locate (' $cityid ', Cityid)";

Cityid is the database tutorial field name that holds data such as 11,12,11,41,25,33. If we're going to take advantage of not in SQL in, that's not true.
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