/// <summary>
/// Get data for replication since the last time it was modified
/// </summary>
/// <param name="tableName">Name of the table to get the replication data from</param>
/// <param name="lastSyncDate">Value of the last time the data was syncronized</param>
/// <param name="hasLastModifiedColumn">identifies whether of not the object contains the last modifed column</param>
/// <returns></returns>
public IEnumerable <DataEntity> GetReplicationDataRetrieve(string tableName, DateTime lastSyncDate, bool hasLastModifiedColumn)
{
//create the select query
string query = "SELECT * FROM [" + tableName + "]";
//check if the last modified column name is specified
if (hasLastModifiedColumn)
{
//round the milliseconds to the nearest second
if (lastSyncDate.Millisecond > 0)
{
lastSyncDate = lastSyncDate.AddSeconds(1);
}
if (lastSyncDate.Kind != DateTimeKind.Utc)
{
lastSyncDate = lastSyncDate.ToUniversalTime();
}
query += " WHERE [ModifiedOn] > convert(datetime, '" + lastSyncDate.ToString("s") + "')";
}
//check if there is an open connection
if (IsConnected)
{
//create the command to request data
OleDbCommand oleDbCommand = new OleDbCommand();
oleDbCommand.CommandText = query;
oleDbCommand.Connection = _connection;
//execute the reader
OleDbDataReader dataReader = oleDbCommand.ExecuteReader();
//check that the reader is not null and that rows were returned
if (dataReader != null && dataReader.HasRows)
{
int fieldsReturned = dataReader.FieldCount;
//perform reading of data while get rows from the reader
while (dataReader.Read())
{
//create a new data entity for each row that is being read
DataEntity dataEntity = new DataEntity(tableName);
//parse through each field in the row
for (int i = 0; i < fieldsReturned; i++)
{
//get the name of the column
var columnName = dataReader.GetName(i);
//get the value of the column in its correct datatype
var dataValue = dataReader.GetProviderSpecificValue(i);
//add the column information to the data enitity
dataEntity.Properties.Add(columnName, dataValue);
}
//yield the data entity, this allows for data to be processed while more data is being retrieved
yield return(dataEntity);
}
}
}
}
/// <summary>
/// Execute the query provided
/// </summary>
/// <param name="tableName">name of the parent table that the query is being executed for</param>
/// <param name="query">query to execute</param>
/// <param name="foreignKeyRelations">list of relations and foreign key values</param>
/// <returns>enumerated list of data entities</returns>
public IEnumerable <DataEntity> Execute(string tableName, string query, Dictionary <string, string> foreignKeyRelations)
{
//check if there is an open connection
if (IsConnected)
{
//create the command to request data
OleDbCommand oleDbCommand = new OleDbCommand();
oleDbCommand.CommandText = query;
oleDbCommand.Connection = _connection;
//execute the reader
OleDbDataReader dataReader = oleDbCommand.ExecuteReader();
using (dataReader)
{
//check that the reader is not null and that rows were returned
if (dataReader != null && dataReader.HasRows)
{
int fieldsReturned = dataReader.FieldCount;
//perform reading of data while get rows from the reader
while (dataReader.Read())
{
//create a new data entity for each row that is being read
DataEntity dataEntity = new DataEntity(tableName);
//parse through each field in the row
for (int i = 0; i < fieldsReturned; i++)
{
if (ParseRelationships(dataEntity, i, dataReader))
{
continue;
}
//get the name of the column
var columnName = dataReader.GetName(i);
//get the value of the column in its correct datatype
var dataValue = dataReader.GetProviderSpecificValue(i);
//convert DB Null values to standard null values
if (dataValue == DBNull.Value)
{
dataValue = null;
}
//add the column information to the data enitity
dataEntity.Properties.Add(columnName, dataValue);
}
ValidateEntityRelations(dataEntity, foreignKeyRelations);
//yield the data entity, this allows for data to be processed while more data is being retrieved
yield return(dataEntity);
}
}
}
}
}
