我正在用php和mysql计算一列的记录总数。如果没有找到记录,我想返回零,但是我一直收到此错误
致命错误:消息未捕获的异常“ PDOException” 'SQLSTATE [42883]:未定义的函数:7错误:运算符没有 存在:
character varying LINE 1: SELECT IFNULL(COUNT(
school_name), 'follow')
answer` as s ... ^提示:没有运算符匹配给定名称 和参数类型。您可能需要添加显式类型转换。在
SQL
$row = $conn->query("SELECT IFNULL(Count(school_name), '0') as school_total from schools_tbl");
$row->setFetchMode(PDO::FETCH_ASSOC);
$school_count = $row->fetchColumn();