MySQL 5.7

By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.

select version();

version()

5.7.35

Set @str = 'abc;sdifh;1231;hsjh;wque';
select SUBSTRING(@str,0,INSTR(@str,';'));
select SUBSTRING(@str,1,INSTR(@str,';'));

SUBSTRING(@str,0,INSTR(@str,';'))

SUBSTRING(@str,1,INSTR(@str,';'))

abc;

CREATE FUNCTION count_Occurrence(str varchar(1000),x varchar(20)) RETURNS INT
BEGIN
    SET  @cn = 0;
    WHILE (INSTR(str,x) <> 0) DO
        SET @cn = @cn + 1;
        SET str = REPLACE(str,SUBSTRING(str,1,INSTR(str,x)),"");
    END WHILE;
    RETURN @cn;
END
SELECT count_Occurrence('abc;sdifh;1231;hsjh;wque', ';') AS found

found

4