带H2的Scala Slikk 0.11.2计数

Question

我试图用https://github.com/slick/slick-examples/blob/master/src/main/scala/scala/slick/examples/lifted/firstexample.scala：

// Definition of the SUPPLIERS table
object Suppliers extends Table[(Int, String, String, String, String, String)]("SUPPLIERS")        {
  def id = column[Int]("SUP_ID", O.PrimaryKey) // This is the primary key column
  def name = column[String]("SUP_NAME")
  def street = column[String]("STREET")
  def city = column[String]("CITY")
  def state = column[String]("STATE")
  def zip = column[String]("ZIP")
  // Every table needs a * projection with the same type as the table's type parameter
  def * = id ~ name ~ street ~ city ~ state ~ zip
}

// Definition of the COFFEES table
object Coffees extends Table[(String, Int, Double, Int, Int)]("COFFEES") {
  def name = column[String]("COF_NAME", O.PrimaryKey)
  def supID = column[Int]("SUP_ID")
  def price = column[Double]("PRICE")
  def sales = column[Int]("SALES")
  def total = column[Int]("TOTAL")
  def * = name ~ supID ~ price ~ sales ~ total
  // A reified foreign key relation that can be navigated to create a join
  def supplier = foreignKey("SUP_FK", supID, Suppliers)(_.id)
}

// Connect to the database and execute the following block within a session
Database.forURL("jdbc:h2:mem:test1", driver = "org.h2.Driver") withSession {

  (Suppliers.ddl ++ Coffees.ddl).create

  // Insert some suppliers
  Suppliers.insert(101, "Acme, Inc.",      "99 Market Street", "Groundsville", "CA", "95199")
  Suppliers.insert( 49, "Superior Coffee", "1 Party Place",    "Mendocino",    "CA", "95460")
  Suppliers.insert(150, "The High Ground", "100 Coffee Lane",  "Meadows",      "CA", "93966")

  // Insert some coffees (using JDBC's batch insert feature, if supported by the DB)
  Coffees.insertAll(
    ("Colombian",         101, 7.99, 0, 0),
    ("French_Roast",       49, 8.99, 0, 0),
    ("Espresso",          150, 9.99, 0, 0),
    ("Colombian_Decaf",   101, 8.99, 0, 0),
    ("French_Roast_Decaf", 49, 9.99, 0, 0)
  )

  /**** This part works fine */
  val query = for (c <- Coffees) yield c
  query foreach println
  /*********/

  /******This one fails */
  val query1 = for (c <- Coffees) yield c.length
  println("query1 = " + query1.list.head)

    Column "X4.COF_NAME" not found; SQL statement:
    CREATE FORCE VIEW PUBLIC._1 AS
    SELECT
        X4.COF_NAME,
        X4.SUP_ID,
        X4.PRICE,
        X4.SALES,
        X4.TOTAL
    FROM SYSTEM_RANGE(1, 1) [42122-168]
    org.h2.jdbc.JdbcSQLException: Column "X4.COF_NAME" not found; SQL statement:
    CREATE FORCE VIEW PUBLIC._1 AS
    SELECT
        X4.COF_NAME,
        X4.SUP_ID,
        X4.PRICE,
        X4.SALES,
        X4.TOTAL
    FROM SYSTEM_RANGE(1, 1) [42122-168]
        at org.h2.message.DbException.getJdbcSQLException(DbException.java:329)
        at org.h2.message.DbException.get(DbException.java:169)
        at org.h2.message.DbException.get(DbException.java:146)
        at org.h2.expression.ExpressionColumn.optimize(ExpressionColumn.java:138)
        at org.h2.command.dml.Select.prepare(Select.java:799)
        at org.h2.command.Parser.prepare(Parser.java:202)
        at org.h2.engine.Session.prepare(Session.java:388)
        at org.h2.engine.Session.prepare(Session.java:375)
        at org.h2.table.TableView.compileViewQuery(TableView.java:99)
        at org.h2.table.TableView.initColumnsAndTables(TableView.java:144)
        at org.h2.table.TableView.init(TableView.java:95)
        at org.h2.table.TableView.(TableView.java:61)
        at org.h2.table.TableView.createTempView(TableView.java:420)
        at org.h2.command.Parser.readTableFilter(Parser.java:1037)
        at org.h2.command.Parser.parseSelectSimpleFromPart(Parser.java:1690)
        at org.h2.command.Parser.parseSelectSimple(Parser.java:1797)
        at org.h2.command.Parser.parseSelectSub(Parser.java:1684)
        at org.h2.command.Parser.parseSelectUnion(Parser.java:1527)
        at org.h2.command.Parser.readTableFilter(Parser.java:1026)
        at org.h2.command.Parser.parseSelectSimpleFromPart(Parser.java:1690)
        at org.h2.command.Parser.parseSelectSimple(Parser.java:1797)
        at org.h2.command.Parser.parseSelectSub(Parser.java:1684)
        at org.h2.command.Parser.parseSelectUnion(Parser.java:1527)
        at org.h2.command.Parser.parseSelect(Parser.java:1515)
        at org.h2.command.Parser.parsePrepared(Parser.java:405)
        at org.h2.command.Parser.parse(Parser.java:279)
        at org.h2.command.Parser.parse(Parser.java:251)
        at org.h2.command.Parser.prepareCommand(Parser.java:217)
        at org.h2.engine.Session.prepareLocal(Session.java:415)
        at org.h2.engine.Session.prepareCommand(Session.java:364)
        at org.h2.jdbc.JdbcConnection.prepareCommand(JdbcConnection.java:1109)
        at org.h2.jdbc.JdbcPreparedStatement.(JdbcPreparedStatement.java:74)
        at org.h2.jdbc.JdbcConnection.prepareStatement(JdbcConnection.java:626)
        at scala.slick.session.Session$class.prepareStatement(Session.scala:29)
        at scala.slick.session.BaseSession.prepareStatement(Session.scala:201)
        at scala.slick.jdbc.StatementInvoker.results(StatementInvoker.scala:29)
        at scala.slick.jdbc.StatementInvoker.elementsTo(StatementInvoker.scala:17)
        at scala.slick.jdbc.Invoker$class.foreach(Invoker.scala:90)
        at scala.slick.jdbc.StatementInvoker.foreach(StatementInvoker.scala:10)
        at scala.slick.jdbc.Invoker$class.build(Invoker.scala:66)
        at scala.slick.jdbc.StatementInvoker.build(StatementInvoker.scala:10)
        at scala.slick.jdbc.Invoker$class.list(Invoker.scala:56)
        at scala.slick.jdbc.StatementInvoker.list(StatementInvoker.scala:10)
        at scala.slick.jdbc.UnitInvoker$class.list(Invoker.scala:150)
        at scala.slick.driver.BasicInvokerComponent$QueryInvoker.list(BasicInvokerComponent.scala:19)

如果使用

println("query1 = " + query1.firstOption.getOrElse(0))

还有...

Answer 1

你试过以下方法吗？

val query1 = for (c <- Coffees) yield c.name.count
println("query1 = " + query1.firstOption.getOrElse(0))

它背后的配方是c.primary-key.count；在本例中，name是coffees的主键。