edu.ucsb.nceas.dbadapter

## Class AbstractDatabase

- java.lang.Object
- - edu.ucsb.nceas.dbadapter.AbstractDatabase

- Direct Known Subclasses:
    OracleAdapter, PostgresqlAdapter, SqlserverAdapter

      public abstract class AbstractDatabase
      extends java.lang.Object

  Java offers uniform database access through the use of JDBC. But many databases still use different SQL implementations and conventions. Thus this class offers extended programming interface that all subclasses should implement to gain access to different databases. To add a new database adapter class you must create a new class Adapter that extends edu.ucsb.nceas.dbadapter.AbstarctDatabase (where dbname is the name of the database or database driver you wish to add to your application). AbstarctDatabase is an abstract class, thus the subclasses need to implement the abstract methods.

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `AbstractDatabase()`

  - ### Method Summary

    All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `static java.lang.Object` | `createObject(java.lang.String className)` Instantiate a class using the name of the class at runtime
    `abstract java.lang.String` | `getDateTimeFunction()` The function name that gets the current date and time from the database server
    `abstract java.lang.String` | `getIsNULLFunction()` The function name that is used to return non-NULL value
    `abstract java.lang.String` | `getLeftJoinQuery(java.lang.String selectFields, java.lang.String tableA, java.lang.String tableB, java.lang.String joinCriteria, java.lang.String nonJoinCriteria)` Syntax for doing a left join Add 'a.' in front of the fields for first table and 'b.' in front of the fields for the second table
    `abstract java.lang.String` | `getPagedQuery(java.lang.String queryWithOrderBy, java.lang.Integer start, java.lang.Integer count)` for generating a query for paging
    `abstract java.lang.String` | `getReplicationDocumentListSQL()` This method will return the sql command to get document list in xml_document in replication.
    `abstract java.lang.String` | `getStringDelimiter()` The character that the specific database implementation uses to indicate string literals in SQL.
    `abstract long` | `getUniqueID(java.sql.Connection conn, java.lang.String tableName)` Unique ID generator
    `static void` | `main(java.lang.String[] args)` the main routine used to test the dbadapter utility.
    `java.lang.String` | `toDate(java.lang.String dateString, java.lang.String format)` MSSQL didn't support to_date function which to transfer a text string to date type.

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Constructor Detail

    - #### AbstractDatabase

          public AbstractDatabase()

  - ### Method Detail

    - #### getUniqueID

          public abstract long getUniqueID(java.sql.Connection conn,
                                           java.lang.String tableName)
                                    throws java.sql.SQLException

      Unique ID generator
      Parameters:
        `conn` - db connection in which the unique id was generated
        `tableName` - the table which unique id was generate
      Returns:
        return the generated unique id as a long type
      Throws:
        `java.sql.SQLException` -
        any SQLException that can be thrown during the db operation

    - #### getDateTimeFunction

          public abstract java.lang.String getDateTimeFunction()

      The function name that gets the current date and time from the database server
      Returns:
        return the current date and time function name

    - #### getIsNULLFunction

          public abstract java.lang.String getIsNULLFunction()

      The function name that is used to return non-NULL value
      Returns:
        return the non-NULL function name

    - #### getStringDelimiter

          public abstract java.lang.String getStringDelimiter()

      The character that the specific database implementation uses to indicate string literals in SQL. This will usually be a single qoute (').
      Returns:
        return the string delimiter

    - #### toDate

          public java.lang.String toDate(java.lang.String dateString,
                                         java.lang.String format)

      MSSQL didn't support to_date function which to transfer a text string to date type. But Oracle and Postsql do.

    - #### getLeftJoinQuery

          public abstract java.lang.String getLeftJoinQuery(java.lang.String selectFields,
                                                            java.lang.String tableA,
                                                            java.lang.String tableB,
                                                            java.lang.String joinCriteria,
                                                            java.lang.String nonJoinCriteria)

      Syntax for doing a left join Add 'a.' in front of the fields for first table and 'b.' in front of the fields for the second table
      Parameters:
        `selectFields` - fields that you want to be selected
        `tableA` - first table in the join
        `tableB` - second table in the join
        `joinCriteria` - the criteria based on which the join will be made
        `nonJoinCriteria` - all other criterias
      Returns:
        return the string for teh select query

    - #### createObject

          public static java.lang.Object createObject(java.lang.String className)
                                               throws java.lang.Exception

      Instantiate a class using the name of the class at runtime
      Parameters:
        `className` - the fully qualified name of the class to instantiate
      Throws:
        `java.lang.Exception`

    - #### main

          public static void main(java.lang.String[] args)

      the main routine used to test the dbadapter utility.

    - #### getReplicationDocumentListSQL

          public abstract java.lang.String getReplicationDocumentListSQL()

      This method will return the sql command to get document list in xml_document in replication. Because it involes outer join, so this method is very flexible.
      Returns:

    - #### getPagedQuery

          public abstract java.lang.String getPagedQuery(java.lang.String queryWithOrderBy,
                                                         java.lang.Integer start,
                                                         java.lang.Integer count)

      for generating a query for paging
      Parameters:
        `queryWithOrderBy` - - the complete query with SELECT, FROM, WHERE and ORDER BY clauses
        `start` - the row number to start from
        `count` - the number of records from start to return
      Returns:
        query specific to the RDBMS in use

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