[英]MySql - Create view to read from Multiple Tables
我已經為發票開出了一些舊的行項目,這些行項不再是最新的,但仍需要引用它們。 我認為我需要創建一個VIEW,但並不是真正了解它。 有人可以幫忙,以便我可以運行查詢以提取發票,然后提取所有已分配的訂單項的總和(無論項目位於哪個表中)?
CREATE TABLE `Invoice` (
`Invoice_ID` INT(11) UNSIGNED NOT NULL AUTO_INCREMENT,
`Invoice_CreatedDateTime` DATETIME DEFAULT NULL,
`Invoice_Status` ENUM('Paid','Sent','Unsent','Hold') DEFAULT NULL,
`LastUpdatedAt` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
PRIMARY KEY (`ID`),
KEY `LastUpdatedAt` (`LastUpdatedAt`)
) ENGINE=MYISAM DEFAULT CHARSET=latin1
CREATE TABLE `Invoice_LineItem` (
`LineItem_ID` INT(11) UNSIGNED NOT NULL AUTO_INCREMENT,
`LineItem_ChargeType` VARCHAR(64) NOT NULL DEFAULT '',
`LineItem_InvoiceID` INT(11) UNSIGNED DEFAULT NULL,
`LineItem_Amount` DECIMAL(11,4) DEFAULT NULL,
`LastUpdatedAt` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
PRIMARY KEY (`LineItem_ID`),
KEY `LastUpdatedAt` (`LastUpdatedAt`),
KEY `LineItem_InvoiceID` (`LineItem_InvoiceID`)
) ENGINE=MYISAM AUTO_INCREMENT=1 DEFAULT CHARSET=latin1
CREATE TABLE `Invoice_LineItem_Archived` (
`LineItem_ID` INT(11) UNSIGNED NOT NULL AUTO_INCREMENT,
`LineItem_ChargeType` VARCHAR(64) NOT NULL DEFAULT '',
`LineItem_InvoiceID` INT(11) UNSIGNED DEFAULT NULL,
`LineItem_Amount` DECIMAL(11,4) DEFAULT NULL,
`LastUpdatedAt` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
PRIMARY KEY (`LineItem_ID`),
KEY `LastUpdatedAt` (`LastUpdatedAt`),
KEY `LineItem_InvoiceID` (`LineItem_InvoiceID`)
) ENGINE=MYISAM AUTO_INCREMENT=1 DEFAULT CHARSET=latin1
通常,我只運行以下查詢以獲取發票上的應付金額
SELECT
Invoice_ID,
Invoice_CreatedDateTime,
Invoice_Status,
(SELECT SUM(LineItem_Amount) AS totAmt FROM Invoice_LineItem WHERE LineItem_InvoiceID=Invoice_ID) AS Invoice_Total
FROM
Invoice
WHERE
Invoice_Status='Sent'
另外,如何在一個查詢中從兩個表中選擇所有訂單項?
SELECT
LineItem_ID,
LineItem_ChargeType,
LineItem_Amount
FROM
Invoice_LineItem
WHERE
LineItem_InvoiceID='1234'
您可以使用MERGE Storage Engine創建一個虛擬表,該表是兩個實際表的結合:
CREATE TABLE Invoice_LineItem_All
(
`LineItem_ID` INT(11) UNSIGNED NOT NULL AUTO_INCREMENT,
`LineItem_ChargeType` VARCHAR(64) NOT NULL DEFAULT '',
`LineItem_InvoiceID` INT(11) UNSIGNED DEFAULT NULL,
`LineItem_Amount` DECIMAL(11,4) DEFAULT NULL,
`LastUpdatedAt` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
KEY (`LineItem_ID`),
KEY `LastUpdatedAt` (`LastUpdatedAt`),
KEY `LineItem_InvoiceID` (`LineItem_InvoiceID`)
) ENGINE=MERGE UNION=(Invoice_LineItem_Archived, Invoice_LineItem);
您可以使用UNION
:
SELECT a.* FROM a
UNION
SELECT b.* FROM b;
您只需要在不同的查詢中使用相同數量和類型的列即可。 據我所知,您可以在子查詢中添加測試,但是我不確定是否可以對全局結果進行訂購。
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