SQL Delete Statement Syntax and Usage

Note

This feature is only available in NCache Enterprise Edition.

Similar to SQL, NCache lets you delete the data from the cache based on the given criteria. The delete statement is executed through ExecuteNonQuery which returns the number of the deleted rows as a result of the query executed.

Note

The Delete statement can only be executed through ExecuteNonQuery:

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

Here's an example which deletes all the products from the cache with the UnitsInStock equals to 0 using ExecuteNonQuery.

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 = "DELETE FROM FQN.Product WHERE UnitsInStock = 0";

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

    // Execute query
    cache.SearchService.ExecuteNonQuery(queryCommand);
}
catch (OperationFailedException ex)
{
    if (ex.ErrorCode == NCacheErrorCodes.INCORRECT_FORMAT)
    {
        // Make sure that the query format is correct
    }
    else
    {
        // Exception can occur due to:
        // Any other query executed except DELETE
        // 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 = "DELETE FROM FQN.Product WHERE UnitsInStock = 0";

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

    // Execute query
    cache.getSearchService().executeNonQuery(queryCommand);
}
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 = "DELETE FROM FQN.Product WHERE UnitsInStock = 0";

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

    // Execute query
    await ( await this.cache.getSearchService()).executeNonQuery(queryCommand);
} 
catch (error)
{
    // Handle errors
}

Additional Resources

NCache provides sample application for SQL Searching on GitHub.

SQL Delete Statement Syntax and Usage

Note

Note

Pre-Requisites

Syntax

Additional Resources

See Also