Question

我有一个包含多行的sql表，我想将他的某些行合并为一行，如果行列不同，则返回“混合值”，否则返回列值

示例：

SQL Table

如果我选择ID为1和2的行，我希望结果是这样

Table Resutls

如果我选择ID为1,2和3的行

Table Resutls

先感谢

Answer 1

您可以尝试使用group_concat（distinct（））

import com.sun.net.httpserver.*
import java.io.IOException
import java.io.InputStream
import java.io.OutputStream
import java.net.HttpURLConnection
import java.net.InetSocketAddress
import java.net.URL
import java.util.*
import javax.net.ssl.HttpsURLConnection
import kotlin.system.measureNanoTime
import kotlin.system.measureTimeMillis

fun main(args: Array<String>) {

    val PORT = 49831

    val serverT = Thread {
        val s = HttpServer.create()
        s.bind(InetSocketAddress(PORT),0)
        s.executor = null
        s.createContext("/") {httpExchange ->
            val request = httpExchange.requestBody.readBytes()
            val response = "This is the response".toByteArray()
            val headers = httpExchange.getResponseHeaders()
            headers.add("Access-Control-Allow-Methods","OPTIONS,GET,POST")
            headers.add("Access-Control-Allow-Origin","*")
            httpExchange.sendResponseHeaders(200, response.size.toLong())
            val os = httpExchange.responseBody
            os.write(response)
            os.close()
            println("Server: Finished sending response.")
            s.stop(0)
        }
        s.start()
    }

    serverT.start()

    val client = TestHttpClient("127.0.0.1", PORT)
    val byteArr = ByteArray(1024*1024*100) {'a'.toByte()}
    client.sendRequestSynchronous(byteArr.inputStream(), requestMethod = "POST", measureSpeed = {it ->
        println("Avg speed: ${it.getOverallTransferRate()} MB/s")
    })
}

class TestHttpClient (val serverHostname: String, val serverPort: Int) {

    /**
     * Sends a request to the server with the content of the data InputStream, at the specified uri. You can specify the request method and add any headers on the request by using the respective parameters.
     * @param data The data input stream that will be sent to the server
     * @param uri The URI that the request will be sent to
     * @param requestMethod The type of the HTTP request
     * @param headers The headers of the request
     * @param measureSpeed A function which is being called to update the statistics of this request
     */
    fun sendRequestSynchronous(data: InputStream, uri: String = "/", requestMethod: String = "POST", headers: Map<String, String> = HashMap(), measureSpeed : (NetworkStatistics) -> Unit = { }) : Triple<Int, MutableMap<String, MutableList<String>>, InputStream> {
        val path = "http://$serverHostname:$serverPort$uri"
        val connection = if (path.startsWith("https://")) (URL(path).openConnection() as HttpsURLConnection) else URL(path).openConnection() as HttpURLConnection

        connection.doInput = true
        connection.doOutput = true
        connection.requestMethod = requestMethod
        //connection.setChunkedStreamingMode(64*1024) // Uncomment this line to have a better measurement of the speed
        headers.forEach {
            connection.addRequestProperty(it.key, it.value)
        }
        connection.connect()
        println("Client connected!")

        val totalAmountBytesToSend = data.available() // amount of bytes of the whole request
        val statistics = NetworkStatistics(totalAmountBytesToSend.toLong())
        val timeMeas = measureTimeMillis {
            copy(data, connection.outputStream, statistics, {it -> measureSpeed(it)} )
        }

        println("Time measured for upload: $timeMeas")

        val timeMeas2 = measureTimeMillis {
            connection.outputStream.flush()
        }

        println("Time measured for flushing output stream: $timeMeas2")

        var code = 200
        val timeMeas3 = measureTimeMillis {
            code = connection.responseCode
        }

        println("Time measured for reading the connection response code: $timeMeas3")
        return Triple(code, connection.headerFields, connection.inputStream)
    }

    private val BUFFER_SIZE = 8192

    @Throws(IOException::class)
    private fun copy(source: InputStream, sink: OutputStream, networkStatistics: NetworkStatistics, measureSpeed : (NetworkStatistics) -> Unit = { }): Long {
        var nread = 0L
        val buf = ByteArray(BUFFER_SIZE)
        var n: Int
        n = source.read(buf)
        while (n > 0) {
            val nano = measureNanoTime {
                sink.write(buf, 0, n)
                nread += n.toLong()
                n = source.read(buf)
            }
            networkStatistics.dataSent = nread
            networkStatistics.totalSendingTime += nano
            networkStatistics.lastPacketBytes = n.toLong()
            networkStatistics.lastPacketTime = nano
            measureSpeed(networkStatistics)
        }
        return nread
    }
}

class NetworkStatistics(var totalAmountData: Long, var dataSent: Long = 0, var totalSendingTime: Long = 0, var lastPacketBytes: Long = 0, var lastPacketTime: Long = 0) {

    private fun convertNanoToSeconds(nano: Long) : Double {
        return nano.toDouble() / 1000000000
    }

    private fun convertBytesToMegabytes(bytes: Long) : Double {
        return bytes.toDouble()/1048576
    }

    private fun convertBytesNanoToMegabytesSeconds(bytes: Long, nano: Long) : Double {
        return ( bytes.toDouble() / nano.toDouble() ) * 953.67431640625
    }

    /**
     * Returns the transfer rate of the last packet in MB per second.
     */
    fun getLastPacketRate() : Double {
        return if (lastPacketTime != 0L) {
            convertBytesToMegabytes(lastPacketBytes) / convertNanoToSeconds(lastPacketTime)
        }
        else
            0.0
    }

    /**
     * Returns the transfer rate that has been measured by this instance in MB per second.
     */
    fun getOverallTransferRate() : Double {
        return if (totalSendingTime != 0L) {
            convertBytesNanoToMegabytesSeconds(dataSent, totalSendingTime)
        }
        else
            0.0
    }

    /**
     * Returns the percent of the transfer that has been completed.
     */
    fun getTransferCompletePercent() : Double {
        return if (totalAmountData != 0L) {
            (dataSent.toDouble() / totalAmountData) * 100
        }
        else
            0.0
    }
}

Answer 2

您可以结合使用[^0-9]*和CASE WHEN来获取所需的内容。尚不清楚是要按COUNT(DISTINCT)还是按price_id进行分组，但我会假设是这样。

service_id

MySQL：如何合并多行以仅返回一行

2 个答案: