从多个表中搜索单列 [英] Search single column from multiple table

问题描述

我正在使用此代码从单个表中搜索。但如何通过文本框从2表中搜索员工ID。我的桌子是ict_table和finance_table

从ict_table中选择* where staff_id ='& id.Text&'

我尝试过：



是..当我只从单个表中搜索时它的工作。

解决方案

从不这样做开始：永远不要连接字符串来构建一个SQL命令。它让您对意外或故意的SQL注入攻击敞开大门，这可能会破坏整个数据库。请使用参数化查询。



当您连接字符串时，会导致问题，因为SQL会收到如下命令：

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

就SQL而言，用户添加的引用会终止字符串，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：

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

哪个SQL看作三个单独的命令：

  SELECT  *  FROM  MyTable  WHERE  StreetAddress = '  x'; 

完全有效的SELECT

  DROP   TABLE  MyTable; 

完全有效的删除表格通讯和

   -   ' 

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？



如果你想从两张桌子中检索结果，那就试试这个：

< pre lang =SQL> SELECT a。*，b。* FROM ict_table a
JOIN other_table b ON a.staff_id = b.staff_id
WHERE a.staff_ID = @ ID

并查看是否能满足您的需求。

im using this code to search from single table. but how to search staff id from 2 table through textbox. my table is ict_table and finance_table

Select * from ict_table where staff_id = '" & id.Text & "'"

What I have tried:

yes.. its work when i search only from single table.

解决方案

Start by not doing it like that: 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. Use Parametrized queries instead.

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

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

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;--'

Which SQL sees as three separate commands:

SELECT * FROM MyTable WHERE StreetAddress = 'x';

A perfectly valid SELECT

DROP TABLE MyTable;

A perfectly valid "delete the table" command

--'

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?

If you are trying to retrieve result from two tables then try this:

SELECT a.*, b.* FROM ict_table a
JOIN other_table b ON a.staff_id = b.staff_id
WHERE a.staff_ID = @ID

And see if that gives you what you are looking for.

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