scray.jdbc.extractors.ScraySQLDialect.scala Maven / Gradle / Ivy

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scray adapter to r/w JDBC tables

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package scray.jdbc.extractors

import scray.querying.description.internal.Domain
import scray.querying.description.TableIdentifier
import scray.querying.description.QueryRange

/**
 * Ancestor of all SQL dialects that implement relational DBMS dialects
 */
abstract class ScraySQLDialect(val name: String, unequal: String = "<>") {
  
  /**
   * returns true if the provided jdbcURL is valid for this type of dialect
   */
  def isDialectJdbcURL(jdbcURL: String): Boolean
  
  /**
   * returns the name of this dialect for extraction
   */
  def getName: String = name
  
  /**
   * returns the unequal operator for this relational DBMS
   */
  def getUnequal: String = unequal
  
  /**
   * removes quotes for this relational DBMS, using a default, which removes " and ; and '
   */
  def removeQuotes(in: String): String = in.filterNot(c => c == '"' || c == ';' || c == ''')
  
  /**
   * Returns a formatted Select String for this relational DBMS
   * Warning: default assumption is, that where, group by, order by and limit clauses are directly consecutive
   * as specified in this list
   */
  def getFormattedSelectString(table: TableIdentifier, where: String, limit: String, 
      groupBy: String, orderBy: String): String =
    s"""SELECT * FROM "${removeQuotes(table.dbId)}"."${removeQuotes(table.tableId)}" ${decideWhere(where)} ${groupBy} ${orderBy} ${limit}"""

  /**
   * limits are usually non-standard for DBMS systems, so we leave the implementation
   * open to enforce implementation in concrete dialects
   */
  def getEnforcedLimit(range: Option[QueryRange], where: List[Domain[_]]): (String, List[Domain[_]])
  
  /**
   * if the empty String should be consered to be equal to NULL values
   */
  def emptyStringIsNull: Boolean = false
  
  /**
   * decide whether to place a WHERE in front of the domains
   */
  def decideWhere(where: String): String = if(!where.isEmpty()) s"WHERE $where" else ""

  /**
   * class name of the driver for the database of this dialect
   */
  val DRIVER_CLASS_NAME: String
}