在单个 Declare 语句中选择多个值答案

【问题标题】：Select multiple values within a single Declare statement在单个 Declare 语句中选择多个值
【发布时间】：2016-02-24 17:18:30
【问题描述】：

DECLARE @account VARCHAR(12)  
SET @account = '49943725'  

DECLARE @items VARCHAR(5)  
SET @items = (SELECT item_no FROM transactions   
               WHERE account = @account   
               AND item_no IN ('81','101','108','112','113','118','187','189','190','192','193','194','195'))

SELECT 
    property, CONVERT(VARCHAR(10), account) AS account,
    CONVERT(VARCHAR(5), item_no) AS item_no,
    CONVERT(VARCHAR(9), amount) AS amount,  
    CONVERT(VARCHAR(9), amt_paid) AS amt_paid, 
    status,
    CONVERT(VARCHAR(8), tran_id) AS tran_id, 
    CONVERT(VARCHAR(11), post_date) AS post_date, 
    tran_code, 
    CONVERT(VARCHAR(25), notes) AS notes, 
    clk, invoice, charge_property, * 
FROM 
    transactions 
WHERE 
    account = @account AND item_no = @items

错误：

子查询返回超过 1 个值。当子查询跟随 =、!=、、>= 或子查询用作表达式时，这是不允许的。

【问题讨论】：

关于如何使@items = 多个值的任何提示？

标签： sql variables declare

【解决方案1】：

关于如何使@items = 多个值的任何提示？

否 - VARCHAR(5) 变量只能保存一个值。但是，您可以将列表嵌入为子查询：

SELECT 
     property, 
     CONVERT(VARCHAR(10), account) AS account,
     CONVERT(VARCHAR(5), item_no) AS item_no,
     CONVERT(VARCHAR(9), amount) AS amount,  
     CONVERT(VARCHAR(9), amt_paid) AS amt_paid, status,
     CONVERT(VARCHAR(8), tran_id) AS tran_id, 
     CONVERT(VARCHAR(11), post_date) AS post_date, tran_code, 
     CONVERT(VARCHAR(25), notes) AS notes, clk, invoice, charge_property, *
FROM transactions 
WHERE account = @account 
AND item_no IN (SELECT item_no FROM transactions   
               WHERE account = @account   
               AND item_no IN        
                ('81','101','108','112','113','118','187','189','190','192','193','194','195'))

【讨论】：

【解决方案2】：

您可以使用table variable。

DECLARE @Account VARCHAR(12) = '49943725';
DECLARE @Items TABLE (ItemNo VARCHAR(5));

INSERT @Items (Item_no)
SELECT  item_no 
FROM    transactions   
WHERE   account = @account   
AND     item_no IN ('81','101','108','112','113','118','187','189','190','192','193','194','195');

然后在您的实际查询中使用IN：

AND     item_no IN (SELECT ItemNo FROM @Items);

除非您获取项目的查询比您所显示的更复杂，否则您最好遵循 D Stanley 的建议并将您的查询放在主查询中。

【讨论】：