SQL Like Operator Syntax and Usage

Note

This feature is only available in NCache Enterprise Edition.

NCache allows you to use the SQL like query format using LIKE Operator in the query to search for a specific pattern in a column.

The two wildcards used with the LIKE operator are:

*: Used as a substitute for zero or more characters in the string.
?: Used as a substitute for a single character in the string.

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 searches the cache and retrieves all the products that have their ProductName starting with the letters Shamp and Category starting with the letters Househo using ExecuteReader.

try
{
    // Pre-condition: Cache is already connected
    // Items are already present in the cache
    // Specify the query with the specified criteria.
    // Use the Fully Qualified Name (FQN) of your own custom class
    string query = "SELECT * FROM FQN.Product WHERE ProductName LIKE ? AND Category LIKE ?";

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

    // Providing parameters for query
    queryCommand.Parameters.Add("ProductName", "Shamp*");
    queryCommand.Parameters.Add("Category", "Househo*");

    // 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
        string result = reader.GetValue<string>("ProductID");
        // 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
}

try
{
    // Pre-condition: Cache is already connected
    // Items are already present in the cache
    // Specify the query with the specified criteria.
    // Use the Fully Qualified Name (FQN) of your own custom class
    String query = "SELECT * FROM FQN.Product WHERE ProductName LIKE ? AND Category LIKE ?";

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

    // Providing parameters for query
    queryCommand.getParameters().put("ProductName", "Shamp*");
    queryCommand.getParameters().put("Category", "Househo*");

    // 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
            String result = reader.getValue("productID", String.class);

            // Perform operations
        }
    }
    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
    // Specify the query with the specified criteria.
    // Use the Fully Qualified Name (FQN) of your own custom class
    var query = "SELECT * FROM FQN.Product WHERE ProductName LIKE ? AND Category LIKE ?";

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

    // Providing parameters for query
    let parameter1 = new Map();
    parameter1.set("ProductName", "Shamp*");
    queryCommand.setParameters(parameter1);

    let parameter2 = new Map();
    parameter2.set("Category", "Househo*");
    queryCommand.setParameters(parameter2);

    // 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())
        {
            var result = reader.getValue(1, Number());
            // Perform operations
        }
    } 
    else
    {
        // Null query result set retrieved
    }
}
catch (error)
{
    // Handle errors
}

Additional Resources

NCache provides sample application for SQL Searching on GitHub.

SQL Like Operator Syntax and Usage

Note

Pre-Requisites

Syntax

Additional Resources

See Also