无法使用可调用语句或预准备语句调用 PostgreSQL 函数

Question

我创建了一个 PostgreSQL 函数，该函数在后端进行了测试，它按预期工作。但是，当我尝试通过 Scala 模块调用它时，它说该函数不存在。

Function:

create or replace function testing.compareData(ab integer, b json, tablename varchar) RETURNS void as $$
  DECLARE 
  actualTableName varchar := tablename;
  histTableName varchar:= actualTableName ||'_hist';
  job_id Integer:=0;
begin --<<<< HERE
  set search_path to testing; -- Set the schema name
  execute 'SELECT id FROM '||actualTableName||' WHERE id =$1' into job_id using ab;
  -- if there is data for id in the table then perform below operations
  if job_id is not null then
      execute FORMAT('INSERT INTO %I select * from %I where id = $1',histTableName,actualTableName) USING ab;
      execute FORMAT('DELETE FROM %I where id = $1',actualTableName) USING ab;
      EXECUTE FORMAT('INSERT INTO %I values($1,$2)',actualTableName) USING ab,b;
  -- if id is not present then create a new record in the actualTable
  ELSE    
      EXECUTE FORMAT('INSERT INTO %I values($1,$2)',actualTableName) USING ab,b;
  END IF;

END; --<<<< END HERE
$$ LANGUAGE plpgsql;

Callable Statement方式：

def callingStoredProcedure(message: String, id: Integer, resourceType: String): Unit = {
    val connectionUrl: String = ReadingConfig.postgreDBDetails().get("url").getOrElse("None")
    var conn: Connection = null
    var callableStatement: CallableStatement = null
    try {
      conn = DriverManager.getConnection(connectionUrl)
      callableStatement = conn.prepareCall("{ call testing.compareData( ?,?,? ) }")
      callableStatement.setString(1, message)
      callableStatement.setInt(2, id)
      callableStatement.setString(3, resourceType)
      callableStatement.execute()
    } catch {
      case up: Exception =>
        throw up
    } finally {
      conn.close()
    }
  }  

Prepared Statement方式：

def callDataCompareAndInsertFunction(message: String, id: Integer, resourceType: String): Unit = {
    val connectionUrl: String = ReadingConfig.postgreDBDetails().get("url").getOrElse("None")
    var pstmt: PreparedStatement = null
    var conn: Connection = null
    try {
      conn = DriverManager.getConnection(connectionUrl)
      pstmt = conn.prepareStatement("select testing.compareData(?,?,?)")
      pstmt.setInt(1, id)
      pstmt.setString(2, message)
      pstmt.setString(3, resourceType)
      pstmt.executeQuery()
    }
    catch {
      case e: Exception => throw e
    }
    finally {
      conn.close()
    }
  }  

这里，testing 是我创建函数的架构。当使用这两种方式运行时，它会抛出以下错误：

Exception in thread "main" org.postgresql.util.PSQLException: ERROR: function testing.comparedata(character varying, integer, character varying) does not exist
  Hint: No function matches the given name and argument types. You might need to add explicit type casts.

Answer 1

您的第一个参数不是字符串，因此调用setString(1, ...) 将导致您在问题中引用的错误。

您的第二个参数被声明为json，因此您也不能直接在那里传递字符串值。以下应该可以工作（给定函数定义）：

  pstmt = conn.prepareStatement("select testing.compareData(?,cast(? as json),?)")
  pstmt.setInt(1, id)
  pstmt.setString(2, message)
  pstmt.setString(3, resourceType)

您可能还需要使用pstmt.execute() 而不是executeQuery()，因为您的函数不会返回任何内容。