如何在PDO查詢中獲得列的總和

Question

我想從我的數據庫表中獲得列的總和。但我只得到0.00。我的代碼是：

$total_income_query = $db->prepare("select sum(credit) from accounts WHERE STR_TO_DATE(date, '%d/%m/%Y') BETWEEN STR_TO_DATE(:startDate, '%d/%m/%Y') AND STR_TO_DATE(:endDate, '%d/%m/%Y')"); 

$stmt->bindParam(':startDate',$startDate); 
$stmt->bindParam(':endDate',$endDate); 
$stmt->execute(); 

$total = $stmt->fetch(PDO::FETCH_NUM); 

echo $total_income = $total[0]; 

它應該回顯306700.80。我檢查了查詢。它在數據庫中正常工作，但不在我的PHP腳本中。它出什麼問題了？

Answer 1

OK列，問題是我的PDO的代碼。我應該寫$ total_income_query而不是$ stmt。該代碼應該是這樣的......

$total_income_query = $db->prepare("select sum(credit) from accounts WHERE STR_TO_DATE(date, '%d/%m/%Y') BETWEEN STR_TO_DATE(:startDate, '%d/%m/%Y') AND STR_TO_DATE(:endDate, '%d/%m/%Y')"); 

$total_income_query->bindParam(':startDate',$startDate); 
$total_income_query->bindParam(':endDate',$endDate); 
$total_income_query->execute(); 

$total = $total_income_query->fetch(PDO::FETCH_NUM); 

echo $total_income = $total[0]; 

Answer 2

編輯：我的解釋是錯的，我想。但遺憾的是，不要在數據庫中重新格式化日期。 那就是：我想您存儲日期類型DATE/DATETIME

<?php 
$total_income_query = $db->prepare(" 
    SELECT SUM(credit) 
    from accounts 
    WHERE date BETWEEN STR_TO_DATE(:startDate, '%d/%m/%Y') 
       AND STR_TO_DATE(:endDate, '%d/%m/%Y')"); 

$stmt->bindParam(':startDate',$startDate); 
$stmt->bindParam(':endDate',$endDate); 
$stmt->execute(); 

$total = $stmt->fetch(PDO::FETCH_NUM); 

echo $total_income = $total[0];