mysql昨天、今天、今天以前

 
/**
 * sql条件语句：今天内付款
 * @param  string $field [description]
 * @return string        sql
 */
function yestoday_sql($field = 'pay_time'){
    $t_yestoday = date('Y-m-d',strtotime("-1 day"));
    return "date_format(from_UNIXTIME(`{$field}`),'%Y-%m-%d')='{$t_yestoday}'";
}
/**
 * 今天
 * @param  string $field 字段名
 * @return string        sql
 */
function today_sql($field){
    $t_today = date('Y-m-d', strtotime("today"));
    return "date_format(from_UNIXTIME(`{$field}`),'%Y-%m-%d')='{$t_today}'";
}
/**
 * 今天以前
 * @return string sql
 */
function history_sql($field='reg_time'){
    return "DATE_FORMAT(FROM_UNIXTIME(`{$field}`),'%Y-%m-%d')<DATE_FORMAT(now(),'%Y-%m-%d')";
}