是否可以将大字符串写入Firebird Blob? [英] Is it possible to write large strings to Firebird blob?

问题描述

Firebird的文档暗示您可以将大(> 60K)字符串写入表中的Blob值.所以，如果你有这个:

The documentation for Firebird implies that you can write large (> 60K) strings to a blob value in a table. So if you have this:

CREATE TABLE MyBlobTable (
theId int PRIMARY KEY NOT NULL,
theBlob BLOB SUB_TYPE 1
)

然后这应该工作:

insert into MyBlobTable (theId, theBlob) values (1, '[60K characters in a string]')

(示例受 http://web启发. firebirdsql.org/dotnetfirebird/blob-sub_type-1-reading-example-csharp.html )

但是我发现C#驱动程序和FlameRobin都不能写入该值.您会得到意外的命令结尾"(指向字符串中约32K的位置，这有点可疑)

But I've found that neither C# drivers nor FlameRobin can write this value. You get 'Unexpected end of command' (pointing to a spot about 32K into the string, which is a little suspicious)

我认为有一种特殊的方法可以引用或转义数据值，或者是C#等效于此Java代码(http://www.firebirdfaq.org/faq372/)，其中直接将二进制文件读取到陈述.我对文本数据没有任何幻想，因此可以根据需要将其存储为二进制blob.

I figure there is a special way to quote or escape the data values, or maybe a C# equivalent of this Java code (http://www.firebirdfaq.org/faq372/) where a binary file is read directly into the statement. I'm not doing anything fancy with the text data so I'm open to storing it as a binary blob if needed.

谢谢！

更新:参数化查询"是我一直在寻找的短语.我在做什么:

Update: "parameterized queries" is the phrase that I was looking for. What I'm doing:

FbParameter param = new FbParameter("@blobVal", FbDbType.Text);
param.Value = myLargeString;
String query = "insert into MyBlobTable (theId, theBlob) values (1, @blobVal)";
using (FbConnection conn = [something from my pool]) {
    using (FbCommand cmd = new FbCommand(query, conn)) {
        cmd.Parameters.Add(param);
        cmd.ExecuteNonQuery();
    }
}

推荐答案

您正在查询中直接添加文本.然后有限制:Firebird中的第一个查询文本限制为64 kB，varchar大小也有限制.

You are adding text inline in the query. Then there are limits: first query text in Firebird is limited to 64 kB, there is also a limit to the varchar size.

如果要将更多数据添加到Blob，则需要使用参数化查询将其流式传输到Blob.参见示例: http://www.firebirdsql.org/en/net-examples-of-use/#update_text_blob_field

If you want to add more data to a blob, you need to stream it to the blob using parametrized queries. See for an example: http://www.firebirdsql.org/en/net-examples-of-use/#update_text_blob_field

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