我如何使用像运营商，在一个SQLite查询参数？ [英] How can I use the Like Operator with a Parameter in a SQLite query?

问题描述

我可以通过在LINQPad中输入这个结果来获得我想要的结果：

I can get the result I expect by entering this in LINQPad:

SELECT * FROM WorkTable WHERE WTName LIKE "DSD__20090410014953000%"

（它显示了WTName值为DSD__20090410014953000.xml的记录）

(it shows me the record which has a WTName value of DSD__20090410014953000.xml")

但是试图这样做是编程方式正在尝试。我尝试：

But trying to do this programmatically is proving trying. I tried:

const string qry = "SELECT SiteNum FROM WorkTable WHERE WTName LIKE @wtName%";
using (SQLiteConnection con = new SQLiteConnection(HHSUtils.GetDBConnection()))
{
    con.Open();
    SQLiteCommand cmd = new SQLiteCommand(qry, con);
    cmd.Parameters.Add(new SQLiteParameter("wtName", tableName));
    siteNum = Convert.ToInt32(cmd.ExecuteScalar());
}

...但是会导致应用程序崩溃，日志文件告诉我为什么：

...but it causes the app to crash, and my log file tells me why:

Message: From application-wide exception handler: System.Data.SQLite.SQLiteException: SQL logic error or missing database
near "%": syntax error

因此，也许它认为查询参数被命名为wtName％而不是wtName;但是用空格分隔参数和无论什么操作符（％）不起作用。

So maybe it thinks the query parameter is named "wtName%" instead of "wtName"; but separating the parameter and the "whatever" opertor ("%") with a space doesn't work, either.

我可以通过嵌入查询参数到字符串中，如下所示：

I could go retro/kludgy by just embedding the query parameter into the string like so:

const string qry = String.Format("SELECT SiteNum FROM WorkTable WHERE WTName LIKE {0}%", tableName);

...并且没有查询参数，但恐怕如果我这样做< a href =https://haveibeenpwned.com/ =nofollow> Troy Hunt 会出现在我的房子，在栏杆关于SQL注入时，我躺在床上。

...and doing without the query parameter altogether, but I'm afraid if I did that Troy Hunt would show up at my house and flail me with a bedrail while railing about SQL Injection.

如何获得我的数据并同时写入安全代码？

How can I get my data and simultaneously write safe code?

推荐答案

通配符％应添加到参数值，而不是参数名称

The wildcard % should be added to the parameter value, not to the parameter name

const string qry = "SELECT SiteNum FROM WorkTable WHERE WTName LIKE @wtName";
using (SQLiteConnection con = new SQLiteConnection(HHSUtils.GetDBConnection()))
{
    con.Open();
    SQLiteCommand cmd = new SQLiteCommand(qry, con);
    cmd.Parameters.Add(new SQLiteParameter("@wtName", tableName + "%"));
    siteNum = Convert.ToInt32(cmd.ExecuteScalar());
}

然而，我不知道这是否重要，请使用占位符（@wtName）

And, I am not sure if it matters here, but, usually, I insert the parameter name with the exact name used in the placeholder ( @wtName )

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