SQL Datetime Function Syntax and Usage

Note

This feature is only available in NCache Enterprise Edition.

NCache provides you with an ease of searching the cache by providing parameters in various formats. You can use various functions in a single query for faster cache searching.

You can use DateTime in your query to search the cache with respect to a particular date or time. Make sure that you specify the date in the correct format. NCache supports various date formats, for more detail on these formats please refer to the DateTime Struct provided by Microsoft.

Pre-Requisites

• Indexing for searchable objects and their attributes need to be configured first as explained in Configuring Query Indexes in Administrator's Guide.
• Include the following namespaces in your application:
  • Alachisoft.NCache.Client
  • Alachisoft.NCache.Runtime.Caching
  • Alachisoft.NCache.Client.Services
  • Alachisoft.NCache.Runtime.Exceptions
• The application must be connected to cache before performing the operation.
• Cache must be running.
• Make sure that the data being added is serializable.
• To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.

Modern Syntax

The following example executes a query which searches for all the orders in the cache whose orderDate is lesser than the date specified using ExecuteReader.

try
{
    // Pre-condition: Cache is already connected

    // Create a query which will be executed on the data set
    // Use the Fully Qualified Name (FQN) of your own custom class
    string query = "SELECT * FROM FQN.Order WHERE OrderDate < ?";

    // Use QueryCommand for query execution
    var queryCommand = new QueryCommand(query);

    // Providing parameters to query 
    queryCommand.Parameters.Add("OrderDate", new DateTime (2017, 02, 01));

    // Executing QueryCommand through ICacheReader
    ICacheReader reader = cache.SearchService.ExecuteReader(queryCommand);

    // Check if the result set is not empty
    if (reader.FieldCount > 0)
    {
        while (reader.Read())
        {
            // Get the value of the result set
            int result = reader.GetValue<int>("OrderID");

            // Perform operations
        }
    }
    else
    {
        // Null query result set retrieved
    }
}
catch (OperationFailedException ex)
{
    if (ex.ErrorCode == NCacheErrorCodes.INCORRECT_FORMAT)
    {
        // Make sure that the query format is correct
    }
    else
    {
        // Exception can occur due to:
        // Connection Failures
        // Operation Timeout
        // Operation performed during state transfer
    }
}
catch (Exception ex)
{
    // Any generic exception like ArgumentException, ArgumentNullException
}

Legacy Syntax

Note

Legacy API is only available in NCache Enterprise Edition.

The following example executes a query which searches for all the orders in the cache whose orderDate is lesser than the date specified using ExecuteReader.

try
{
    // Pre-condition: Cache is already connected

    // Create a query which will be executed on the data set
    // Use the Fully Qualified Name (FQN) of your own custom class
    string query = "SELECT FQN.Order WHERE this.OrderDate < ?";

    // Use QueryCommand for query execution
    var queryCommand = new QueryCommand(query);

    // Providing parameters to query 
    queryCommand.Parameters.Add("OrderDate", new DateTime (2017, 02, 01));

    // Executing QueryCommand through ICacheReader
    ICacheReader reader = cache.ExecuteReader(queryCommand);

    // Check if the result set is not empty
    if (reader.FieldCount > 0)
    {
        while (reader.Read())
        {
            // Get the value of the result set
            Order result = reader.GetValue<Order>(1);
            // Perform operations
        }
    }
    else
    {
        // Null query result set retrieved
    }
}
catch (OperationFailedException ex)
{
    if (ex.ErrorCode == NCacheErrorCodes.INCORRECT_FORMAT)
    {
        // Make sure that the query format is correct
    }
    else
    {
        // Exception can occur due to:
        // Connection Failures
        // Operation Timeout
        // Operation performed during state transfer
    }
}
catch (Exception ex)
{
    // Any generic exception like ArgumentException, ArgumentNullException
}

Recommendation: To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.

Additional Resources

NCache provides sample application for SQL Searching at:

• GitHub
• Shipped with NCache: %NCHOME%\samples\dotnet\SearchUsingSQL

See Also

SQL Search for Keys Syntax and Usage
SQL IN Operator Syntax and Usage
SQL Like Operator Syntax and Usage
SQL GROUP BY Syntax and Usage
Query Operators
Search Cache with LINQ