从两个表中查询SQL [英] Sql query from two tables

问题描述

大家好。我有两个访问表（VB6）：SupplierInvoices&销售。它们都有3个常见的字段名称：Date，PLU&数量。我需要通过SQL查询查询两个表，具体日期范围如下（我知道这是错误的，但只是为了给你一个想法）：



rs。打开选择不同的格式（SupplierInvoices.Date，'dd-MMM-yyyy'）作为tDate，Sum（SupplierInvoices.QTY）作为tTotal从SupplierInvoices，格式（Sales.Date，'dd-MMM-yyyy'）作为sDate，Sum （Sales.QTY）作为销售中的sTotal，其中PLU ='& lblPLU.Caption& '和日期之间＃& StartTime& ＃和＃& EndTime& ＃按格式分组（SupplierInvoices.Date，'dd-MMM-yyyy'）;，cn，adOpenKeyset，adLockOptimistic



结果需要从两个表格返回该日期范围的数量字段的总和。我做不到！请帮忙。



我尝试过：

Hi all. I have two tables in access (VB6): SupplierInvoices & Sales. They both have 3 common field names: Date, PLU & Qty. I need to query both tables via SQL query by a specific date range as follows (I know this is wrong, but just to give you an idea):

rs.Open "Select distinct format(SupplierInvoices.Date, 'dd-MMM-yyyy') as tDate, Sum(SupplierInvoices.QTY) as tTotal from SupplierInvoices, format(Sales.Date, 'dd-MMM-yyyy') as sDate, Sum(Sales.QTY) as sTotal from Sales where PLU = '" & lblPLU.Caption & "' and Date Between #" & StartTime & "# and #" & EndTime & "# Group by format(SupplierInvoices.Date, 'dd-MMM-yyyy');", cn, adOpenKeyset, adLockOptimistic

The result needs to return from both tables the sum of the qty fields for that date range. I can't get it right! Please help.

What I have tried:

rs.Open "Select distinct format(SupplierInvoices.Date, 'dd-MMM-yyyy') as tDate, Sum(SupplierInvoices.QTY) as tTotal from SupplierInvoices, format(Sales.Date, 'dd-MMM-yyyy') as sDate, Sum(Sales.QTY) as sTotal from Sales where PLU = '" & lblPLU.Caption & "' and Date Between #" & StartTime & "# and #" & EndTime & "# Group by format(SupplierInvoices.Date, 'dd-MMM-yyyy');", cn, adOpenKeyset, adLockOptimistic

推荐答案

rs.Open "Select distinct format(SupplierInvoices.Date, 'dd-MMM-yyyy') as tDate, Sum(SupplierInvoices.QTY) as tTotal from SupplierInvoices, format(Sales.Date, 'dd-MMM-yyyy') as sDate, Sum(Sales.QTY) as sTotal from Sales where PLU = '" & lblPLU.Caption & "' and Date Between #" & StartTime & "# and #" & EndTime & "# Group by format(SupplierInvoices.Date, 'dd-MMM-yyyy');", cn, adOpenKeyset, adLockOptimistic

不是你问题的解决方案，而是你遇到的另一个问题。

永远不要通过连接字符串来构建SQL查询。迟早，您将使用用户输入来执行此操作，这会打开一个名为SQL注入的漏洞，这对您的数据库很容易并且容易出错。

名称中的单引号你的程序崩溃。如果用户输入像Brian O'Conner这样的名称可能会使您的应用程序崩溃，那么这是一个SQL注入漏洞，崩溃是最少的问题，恶意用户输入，并且它被提升为具有所有凭据的SQL命令。

SQL注入 - 维基百科 [ ^ ]

SQL注入 [ ^ ]

按示例进行SQL注入攻击 [ ^ ]

PHP：SQL注入 - 手册 [ ^ ]

SQL注入预防备忘单 - OWASP [ ^ ]

我该怎么办？解释没有技术术语的SQL注入？ - 信息安全堆栈交换 [ ^ ]

Not a solution to your question, but another problem you have.
Never build an SQL query by concatenating strings. Sooner or later, you will do it with user inputs, and this opens door to a vulnerability named "SQL injection", it is dangerous for your database and error prone.
A single quote in a name and your program crash. If a user input a name like "Brian O'Conner" can crash your app, it is an SQL injection vulnerability, and the crash is the least of the problems, a malicious user input and it is promoted to SQL commands with all credentials.
SQL injection - Wikipedia[^]
SQL Injection[^]
SQL Injection Attacks by Example[^]
PHP: SQL Injection - Manual[^]
SQL Injection Prevention Cheat Sheet - OWASP[^]
How can I explain SQL injection without technical jargon? - Information Security Stack Exchange[^]

首先，为什么要复制信息？这是一个糟糕的想法，导致难以修复的问题...我可能首先看看你的数据设计，看看结构是否真的有意义。



然后 - 正如Patrice T所说 - 永远不会连接字符串来构建SQL命令。它让您对意外或故意的SQL注入攻击持开放态度，这可能会破坏您的整个数据库。总是使用参数化查询。



连接字符串时会导致问题，因为SQL会收到如下命令：

Firstly, why are you duplicating information? That's a poor idea, which leads to problems that get difficult to fix ... I's probably start by looking at your data design, and seeing if the structure actually makes any sense.

Then - as Patrice T has said - never concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Always use Parameterized queries instead.

When you concatenate strings, you cause problems because SQL receives commands like:

SELECT * FROM MyTable WHERE StreetAddress = 'Baker's Wood'

就SQL而言，用户添加的引号会终止字符串，并且您会遇到问题。但情况可能更糟。如果我来并改为输入：x'; DROP TABLE MyTable; - 然后SQL收到一个非常不同的命令：

The quote the user added terminates the string as far as SQL is concerned and you get problems. But it could be worse. If I come along and type this instead: "x';DROP TABLE MyTable;--" Then SQL receives a very different command:

SELECT * FROM MyTable WHERE StreetAddress = 'x';DROP TABLE MyTable;--'

哪个SQL看作三个单独的命令：

Which SQL sees as three separate commands:

SELECT * FROM MyTable WHERE StreetAddress = 'x';

完全有效的SELECT

A perfectly valid SELECT

DROP TABLE MyTable;

完全有效的删除表格通讯和

A perfectly valid "delete the table" command

--'

其他一切都是评论。

所以它确实：选择任何匹配的行，从数据库中删除表，并忽略其他任何内容。



所以总是使用参数化查询！或者准备好经常从备份中恢复数据库。你定期做备份，不是吗？



最后，如果你的数据实际上是不相关的，那就做两个查询：从一个表中选择总和，然后从另一个中选择总和，并将它们一起添加并选择它。除非数据直接相关，否则不要尝试在单个查询中执行此操作，然后使用JOIN。

And everything else is a comment.
So it does: selects any matching rows, deletes the table from the DB, and ignores anything else.

So ALWAYS use parameterized queries! Or be prepared to restore your DB from backup frequently. You do take backups regularly, don't you?

Finally, if your data is actually unrelated, do it as two queries: SELECT the sum from one table, then SELECT the sum from the other, and add them together and SELECT that. Don't try to do it in a single query unless the data is directly related, and then use a JOIN.

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