Kotlin

Use JDBC to connect to CrateDB from Kotlin applications.

About

JDBC is a standard Java API that provides a common interface for accessing databases in Java.

Driver options

Like when using Java, you have two JDBC driver options: The PostgreSQL JDBC Driver and the CrateDB JDBC Driver. PostgreSQL JDBC uses the jdbc:postgresql:// protocol identifier, while CrateDB JDBC uses jdbc:crate://.

Synopsis

example.kt

import java.sql.DriverManager
import java.util.*

fun main() {

    // Connect to database.
    val jdbcUrl = "jdbc:postgresql://localhost:5432/doc?sslmode=disable"
    // val jdbcUrl = "jdbc:crate://localhost:5432/doc?sslmode=disable"

    val connection = DriverManager.getConnection(jdbcUrl, "crate", "crate")

    // Invoke query.
    val query = connection.prepareStatement("SELECT * FROM sys.summits ORDER BY height DESC LIMIT 3")
    val result = query.executeQuery()

    // Display results.
    while (result.next()) {
        val mountain = result.getString("mountain")
        val height = result.getInt("height")
        println("${mountain}: ${height}")
    }

}

build.gradle.kts

plugins {
    java
    kotlin("jvm") version "2.2.20"
    application
}

repositories {
    mavenCentral()
}

dependencies {
    runtimeOnly("org.postgresql:postgresql:42.7.8")
    // runtimeOnly("io.crate:crate-jdbc:2.7.0")
}

java {
    toolchain {
        languageVersion.set(JavaLanguageVersion.of(11))
    }
}

application {
    mainClass = "ExampleKt"
}

kotlin {
    sourceSets.main {
        kotlin.srcDir(".")
    }
}

Start CrateDB using Docker or Podman, then invoke the example program.

docker run --rm --publish=5432:5432 docker.io/crate '-Cdiscovery.type=single-node'

gradle run

SSL connection

Use the sslmode=require parameter, and replace username, password, and hostname with values matching your environment. Also use this variant to connect to CrateDB Cloud.

val jdbcUrl = "jdbc:postgresql://testcluster.cratedb.net:5432/doc?sslmode=require"
// val jdbcUrl = "jdbc:crate://testcluster.cratedb.net:5432/doc?sslmode=require"
val connection = DriverManager.getConnection(jdbcUrl, "admin", "password")