【萬能SQL語句】
```
$sql = "SELECT * FROM user"; // select all data
$sql = "SELECT * FROM user WHERE TO_DAYS( NOW( ) ) - TO_DAYS(create_date) <= 1"; //select yesterday data
$sql = "SELECT * FROM user WHERE DATE_FORMAT(create_date,'%Y%m')=DATE_FORMAT(CURDATE(),'%Y%m')"; //select this month data
$query = $this->db->query($sql);
return $query->result();
```
強SQL查詢用mysql原生語句的優點是資源多,適用于不同開發語言,如果用codeigniter方式的sql,就只適用于php的codeigniter,資源明顯很多,因此難寫很多。
參考:
https://www.cnblogs.com/shuilangyizu/p/8805384.html