php - 比較年份，用substr截取前4位快，還是date('Y')快?
1問題描述：根據始末日期查詢數據，由於資料庫數據量大，用between and很慢，就添加了year,month,day字段，在比較年月日的時候有substr和date兩種方法，兩種都嘗試過每次載入時間都在變化，也沒找到相關的技術文章。理論上是兩種速度都差不多，還是有相對快速的方法？感謝每一個答題者。
2.相關程式碼片段：
//substr
if(substr($startTime,0,4) == substr($endTime,0,4)){
$str .= " L.year = ".substr($startTime,0,4);
if(substr($startTime,4,2) == substr($endTime,4,2)){
$str .= " and L.month = ".substr($startTime,4,2);
if(date('Ynd',strtotime($startTime)) == date('Ynd',strtotime($endTime))){
$str .= " and day = ".date('d',strtotime($startTime));
}else{
$str .= " and log_date between '$startTime' and '$endTime' ";
}
}else{
$str .= " and log_date between '$startTime' and '$endTime' ";
}
}else{
$str .= " L.log_date between $startTime and $endTime";
}
//date
if(date('Y',strtotime($startTime)) == date('Y',strtotime($endTime))){
$str = " where year = ".date('Y',strtotime($startTime));
if(date('Yn',strtotime($startTime)) == date('Yn',strtotime($endTime))){
$str .= " and month = ".date('n',strtotime($startTime));
if(date('Ynd',strtotime($startTime)) == date('Ynd',strtotime($endTime))){
$str .= " and day = ".date('d',strtotime($startTime));
}else{
$str .= " and log_date between '$startTime' and '$endTime' ";
}
}else{
$str .= " and log_date between '$startTime' and '$endTime' ";
}
}else{
$str = " where log_date between '$startTime' and '$endTime' ";
}
