SQL ORDER BY Syntax and Usage

Note

This feature is only available in NCache Enterprise Edition.

NCache provides you with the ability to sort the data according to the given criteria through SQL like query format using ORDER BY clause. The ORDER BY keyword lets you sort the result set in ascending or descending order as specified.

Pre-Requisites

Install the following NuGet packages:
- Alachisoft.NCache.SDK.
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.
For API details, refer to: ICache, ICacheReader, ExecuteReader, SearchService, QueryCommand.
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.
To handle any unseen exceptions, refer to the Troubleshooting section.

Add the following Maven dependencies in your pom.xml file:

<dependency>
    <groupId>com.alachisoft.ncache</groupId>
    <artifactId>ncache-client</artifactId>
    <version>5.2.0</version>
</dependency>

Indexing for searchable objects and their attributes need to be configured first as explained in Configuring Query Indexes in Administrator's Guide.
Import the following packages in your application:
- import com.alachisoft.ncache.client.*;
- import com.alachisoft.ncache.runtime.exceptions.*;
The application must be connected to cache before performing the operation.
Cache must be running.
For API details, refer to: Cache, CacheReader, executeReader, getSearchService(), QueryCommand.
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.
To handle any unseen exceptions, refer to the Troubleshooting section.

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 modules in your application.
- const ncache = require('ncache-client')
The application must be connected to cache before performing the operation.
Cache must be running.
For API details, refer to: Cache, CacheReader, executeReader, getSearchService(), QueryCommand.
To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.
To handle any unseen exceptions, refer to the Troubleshooting section.

Syntax

The following example sorts the products from the cache with UnitPrice greater than 100 based on their UnitsInStock sorted in descending order using ExecuteReader.

try
{
    // Pre-condition: Cache is already connected
    // Items are already present in the cache
    // Provide Fully Qualified Name (FQN) of your custom class 
    string query = "SELECT * FROM FQN.Product WHERE UnitPrice > 100 ORDER BY UnitsInStock DESC";

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

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

    // Check if result set is not empty
    if (reader.FieldCount > 0)
    {
        while (reader.Read())
        {
            // Get the value of the result set
            int result = reader.GetValue<int>("UnitsInStock");
        }
    }
    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:
        // Duplicate values in the ORDERBY clause
        // Same column to be selected twice
        // Connection Failures
        // Operation Timeout
        // Operation performed during state transfer
    }
}
catch (Exception ex)
{
    // Any generic exception like ArgumentException, ArgumentNullException
}

try
{
    // Pre-condition: Cache is already connected
    // Items are already present in the cache
    // Provide Fully Qualified Name (FQN) of your custom class
    String query = "SELECT * FROM FQN.Product WHERE UnitPrice > 100 ORDER BY UnitsInStock DESC";

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

    // Executing QueryCommand through CacheReader
    CacheReader reader = cache.getSearchService().executeReader(queryCommand);

    // Check if result set is not empty
    if (reader.getFieldCount() > 0)
    {
        while (reader.read())
        {
            // Get the value of the result set
            int result = reader.getValue("UnitsInStock", Integer.class);
        }
    }
    else
    {
        // Null query result set retrieved
    }
}
catch (OperationFailedException ex)
{
    if (ex.getErrorCode() == NCacheErrorCodes.INCORRECT_FORMAT)
    {
        // Make sure 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 IllegalArgumentException or NullPointerException
}

// This is an async method
try
{
    // Pre-condition: Cache is already connected
    // Items are already present in the cache
    // Provide Fully Qualified Name (FQN) of your custom class
    var query = "SELECT * FROM FQN.Product WHERE UnitPrice > 100 ORDER BY UnitsInStock DESC";

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

    // Executing QueryCommand through CacheReader
    var searchService = await this.cache.getSearchService();
    var reader = await searchService.executeReader(queryCommand);

    // Check if result set is not empty
    if (reader.getFieldCount() > 0)
    {
        while (reader.read())
        {
            // Get the value of the result set
            var result = reader.getValue(1, Number());
        }
    }
    else
    {
        // Null query result set retrieved
    }
}
catch (error)
{
    // Handle errors
}

Additional Resources

NCache provides sample application for SQL Searching on GitHub.

SQL ORDER BY Syntax and Usage

Note

Pre-Requisites

Syntax

Additional Resources

See Also