mysql儲存函式只返回一個值。要開發返回多個值的儲存過程，需要使用帶有INOUT或OUT引數的儲存過程。咱們先來看一個orders表它的結構：

mysql> desc orders;
+----------------+-------------+------+-----+---------+-------+
| Field          | Type        | Null | Key | Default | Extra |
+----------------+-------------+------+-----+---------+-------+
| orderNumber    |
 
 int(11)     | NO   | PRI | NULL    |       |
| orderDate      | date        | NO   |     | NULL    |       |
| requiredDate   | date        | NO   |     | NULL    |       |
| shippedDate    | date        | YES  |     | NULL    |       |
| status         | varchar(15) | NO   |     | NULL    |       |
 

| comments       | text        | YES  |     | NULL    |       |
| customerNumber | int(11)     | NO   | MUL | NULL    |       |
+----------------+-------------+------+-----+---------+-------+
7 rows in set

然後嘞，咱們來看一個儲存過程，它接受客戶編號，並返回發貨(shipped)，取消(canceled)，解決(resolved)和爭議(disputed)的訂單總數：

DELIMITER $$

CREATE
 
 PROCEDURE get_order_by_cust(
 IN cust_no INT,
 OUT shipped INT,
 OUT canceled INT,
 OUT resolved INT,
 OUT disputed INT)
BEGIN
 -- shipped
 SELECT
            count(*) INTO shipped
        FROM
            orders
        WHERE
            customerNumber = cust_no
                AND status = 'Shipped';

 -- canceled
 SELECT
            count(*) INTO canceled
        FROM
            orders
        WHERE
            customerNumber = cust_no
                AND status = 'Canceled';

 -- resolved
 SELECT
            count(*) INTO resolved
        FROM
            orders
        WHERE
            customerNumber = cust_no
                AND status = 'Resolved';

 -- disputed
 SELECT
            count(*) INTO disputed
        FROM
            orders
        WHERE
            customerNumber = cust_no
                AND status = 'Disputed';

END

其實，除IN引數之外，儲存過程還需要4個額外的OUT引數：shipped, canceled, resolved 和 disputed。 在儲存過程中，使用帶有count函式的select語句根據訂單狀態獲取相應的訂單總數，並將其分配給相應的引數。按著上面的sql，我們如果要使用get_order_by_cust儲存過程，可以傳遞客戶編號和四個使用者定義的變數來獲取輸出值。執行儲存過程後，我們再使用SELECT語句輸出變數值：

+----------+-----------+-----------+-----------+
| @shipped | @canceled | @resolved | @disputed |
+----------+-----------+-----------+-----------+
|       22 |         0 |         1 |         1 |
+----------+-----------+-----------+-----------+
1 row in set

結合實際應用，我們再來看下從PHP程式中呼叫返回多個值的儲存過程：

<?php
/**
 * Call stored procedure that return multiple values
 * @param $customerNumber
 */
function call_sp($customerNumber)
{
    try {
        $pdo = new PDO("mysql:host=localhost;dbname=yiibaidb", 'root', '123456');

        // execute the stored procedure
        $sql = 'CALL get_order_by_cust(:no,@shipped,@canceled,@resolved,@disputed)';
        $stmt = $pdo->prepare($sql);

        $stmt->bindParam(':no', $customerNumber, PDO::PARAM_INT);
        $stmt->execute();
        $stmt->closeCursor();

        // execute the second query to get values from OUT parameter
        $r = $pdo->query("SELECT @shipped,@canceled,@resolved,@disputed")
                  ->fetch(PDO::FETCH_ASSOC);
        if ($r) {
            printf('Shipped: %d, Canceled: %d, Resolved: %d, Disputed: %d',
                $r['@shipped'],
                $r['@canceled'],
                $r['@resolved'],
                $r['@disputed']);
        }
    } catch (PDOException $pe) {
        die("Error occurred:" . $pe->getMessage());
    }
}

call_sp(141);

上述程式碼中，在@符號之前的使用者定義的變數與資料庫連線相關聯，因此它們可用於在呼叫之間進行訪問。

好啦，本次分享就到這裡了。

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