JetBrains/Exposed

repositories {
    // Versions after 0.30.1
    // Versions before 0.30.1 is unavailable for now
    mavenCentral()
}

val exposedVersion: String by project
dependencies {
    implementation("org.jetbrains.exposed:exposed-core:$exposedVersion")
    implementation("org.jetbrains.exposed:exposed-crypt:$exposedVersion")
    implementation("org.jetbrains.exposed:exposed-dao:$exposedVersion")
    implementation("org.jetbrains.exposed:exposed-jdbc:$exposedVersion")
    
    implementation("org.jetbrains.exposed:exposed-jodatime:$exposedVersion")
    // or
    implementation("org.jetbrains.exposed:exposed-java-time:$exposedVersion")
    // or
    implementation("org.jetbrains.exposed:exposed-kotlin-datetime:$exposedVersion")
    
    implementation("org.jetbrains.exposed:exposed-json:$exposedVersion")
    implementation("org.jetbrains.exposed:exposed-money:$exposedVersion")
    implementation("org.jetbrains.exposed:exposed-spring-boot-starter:$exposedVersion")
}

import org.jetbrains.exposed.sql.*
import org.jetbrains.exposed.sql.SqlExpressionBuilder.like
import org.jetbrains.exposed.sql.transactions.transaction

object Users : Table() {
    val id: Column<String> = varchar("id", 10)
    val name: Column<String> = varchar("name", length = 50)
    val cityId: Column<Int?> = (integer("city_id") references Cities.id).nullable()

    override val primaryKey = PrimaryKey(id, name = "PK_User_ID") // name is optional here
}

object Cities : Table() {
    val id: Column<Int> = integer("id").autoIncrement()
    val name: Column<String> = varchar("name", 50)

    override val primaryKey = PrimaryKey(id, name = "PK_Cities_ID")
}

fun main() {
    Database.connect("jdbc:h2:mem:test", driver = "org.h2.Driver", user = "root", password = "")

    transaction {
        addLogger(StdOutSqlLogger)

        SchemaUtils.create(Cities, Users)

        val saintPetersburgId = Cities.insert {
            it[name] = "St. Petersburg"
        } get Cities.id

        val munichId = Cities.insert {
            it[name] = "Munich"
        } get Cities.id

        val pragueId = Cities.insert {
            it.update(name, stringLiteral("   Prague   ").trim().substring(1, 2))
        }[Cities.id]

        val pragueName = Cities.selectAll().where { Cities.id eq pragueId }.single()[Cities.name]
        println("pragueName = $pragueName")

        Users.insert {
            it[id] = "andrey"
            it[name] = "Andrey"
            it[Users.cityId] = saintPetersburgId
        }

        Users.insert {
            it[id] = "sergey"
            it[name] = "Sergey"
            it[Users.cityId] = munichId
        }

        Users.insert {
            it[id] = "eugene"
            it[name] = "Eugene"
            it[Users.cityId] = munichId
        }

        Users.insert {
            it[id] = "alex"
            it[name] = "Alex"
            it[Users.cityId] = null
        }

        Users.insert {
            it[id] = "smth"
            it[name] = "Something"
            it[Users.cityId] = null
        }

        Users.update({ Users.id eq "alex" }) {
            it[name] = "Alexey"
        }

        Users.deleteWhere{ Users.name like "%thing" }

        println("All cities:")

        for (city in Cities.selectAll()) {
            println("${city[Cities.id]}: ${city[Cities.name]}")
        }

        println("Manual join:")
        
        (Users innerJoin Cities)
            .select(Users.name, Cities.name)
            .where {
                (Users.id.eq("andrey") or Users.name.eq("Sergey")) and
                    Users.id.eq("sergey") and Users.cityId.eq(Cities.id)
            }.forEach { 
                println("${it[Users.name]} lives in ${it[Cities.name]}") 
            }

        println("Join with foreign key:")

        (Users innerJoin Cities)
            .select(Users.name, Users.cityId, Cities.name)
            .where { Cities.name.eq("St. Petersburg") or Users.cityId.isNull() }
            .forEach { 
                if (it[Users.cityId] != null) { 
                    println("${it[Users.name]} lives in ${it[Cities.name]}") 
                } 
                else { 
                    println("${it[Users.name]} lives nowhere") 
                } 
            }

        println("Functions and group by:")

        ((Cities innerJoin Users)
            .select(Cities.name, Users.id.count())
            .groupBy(Cities.name)
            ).forEach {
                val cityName = it[Cities.name]
                val userCount = it[Users.id.count()]

                if (userCount > 0) {
                    println("$userCount user(s) live(s) in $cityName")
                } else {
                    println("Nobody lives in $cityName")
                }
            }

        SchemaUtils.drop(Users, Cities)
    }
}

import org.jetbrains.exposed.dao.*
import org.jetbrains.exposed.dao.id.EntityID
import org.jetbrains.exposed.dao.id.IntIdTable
import org.jetbrains.exposed.sql.*
import org.jetbrains.exposed.sql.transactions.transaction

object Users : IntIdTable() {
    val name = varchar("name", 50).index()
    val city = reference("city", Cities)
    val age = integer("age")
}

object Cities: IntIdTable() {
    val name = varchar("name", 50)
}

class User(id: EntityID<Int>) : IntEntity(id) {
    companion object : IntEntityClass<User>(Users)

    var name by Users.name
    var city by City referencedOn Users.city
    var age by Users.age
}

class City(id: EntityID<Int>) : IntEntity(id) {
    companion object : IntEntityClass<City>(Cities)

    var name by Cities.name
    val users by User referrersOn Users.city
}

fun main() {
    Database.connect("jdbc:h2:mem:test", driver = "org.h2.Driver", user = "root", password = "")

    transaction {
        addLogger(StdOutSqlLogger)

        SchemaUtils.create(Cities, Users)

        val stPete = City.new {
            name = "St. Petersburg"
        }

        val munich = City.new {
            name = "Munich"
        }

        User.new {
            name = "a"
            city = stPete
            age = 5
        }

        User.new {
            name = "b"
            city = stPete
            age = 27
        }

        User.new {
            name = "c"
            city = munich
            age = 42
        }

        println("Cities: ${City.all().joinToString { it.name }}")
        println("Users in ${stPete.name}: ${stPete.users.joinToString { it.name }}")
        println("Adults: ${User.find { Users.age greaterEq 18 }.joinToString { it.name }}")
    }
}