A Database Error Occurred

Error Number: 1055

Expression #2 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'medcraveonline_medcravedb.tbl_journals.slNo' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by

SELECT `tbl_journals`.`slug`, `tbl_journals`.`slNo` FROM `tbl_ebooks` JOIN `tbl_journals` ON `tbl_ebooks`.`journal_name` = `tbl_journals`.`slNo` GROUP BY `tbl_journals`.`slug` ORDER BY `tbl_journals`.`slug` ASC

Filename: models/PageModel.php

Line Number: 95