通过具有CLOB绑定的JDBC执行SQL语句 [英] Execute sql statement via JDBC with CLOB binding

问题描述

我有以下查询(列日志的类型为CLOB):

I have the following query (column log is of type CLOB):

UPDATE table SET log=? where id=?

使用setAsciiStream方法将一个长度超过4000个字符的值放入日志列时，上面的查询工作正常.

The query above works fine when using the setAsciiStream method to put a value longer than 4000 characters into the log column.

但是我不想替换该值，而是要附加它，因此我的查询看起来像这样:

But instead of replacing the value, I want to append it, hence my query looks like this:

UPDATE table SET log=log||?||chr(10) where id=?

以上查询不再起作用，并且出现以下错误:

The above query DOES NOT work any more and I get the following error:

java.sql.SQLException: ORA-01461: can bind a LONG value only for insert into a LONG column

推荐答案

在我看来，您必须使用PL/SQL块来执行所需的操作.假设有一个id 1:

It looks to me like you have to use a PL/SQL block to do what you want. The following works for me, assuming there's an entry with id 1:

import oracle.jdbc.OracleDriver;
import java.sql.*;
import java.io.ByteArrayInputStream;

public class JDBCTest {

    // How much test data to generate.
    public static final int SIZE = 8192;

    public static void main(String[] args) throws Exception {

        // Generate some test data.
        byte[] data = new byte[SIZE];
        for (int i = 0; i < SIZE; ++i) {
            data[i] = (byte) (64 + (i % 32));
        }

        ByteArrayInputStream stream = new ByteArrayInputStream(data);

        DriverManager.registerDriver(new OracleDriver());
        Connection c = DriverManager.getConnection(
            "jdbc:oracle:thin:@some_database", "user", "password");

        String sql =
            "DECLARE\n" +
            "  l_line    CLOB;\n" +
            "BEGIN\n" +
            "  l_line := ?;\n" +
            "  UPDATE table SET log = log || l_line || CHR(10) WHERE id = ?;\n" +
            "END;\n";

        PreparedStatement stmt = c.prepareStatement(sql);
        stmt.setAsciiStream(1, stream, SIZE);
        stmt.setInt(2, 1);
        stmt.execute();
        stmt.close();

        c.commit();

        c.close();
    }
}

这篇关于通过具有CLOB绑定的JDBC执行SQL语句的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！