SQL IN Operator: Syntax and Usage
Note
This feature is only available in NCache Enterprise Edition.
In order to search the cache using SQL like query format with IN operator, you can specify multiple attribute values after the IN keyword. It means that ExecuteReader will search the cache for all the attributes provided after the IN keyword.
Prerequisites
- Install the following NuGet package in your application:
- Searchable objects and their attributes must be indexed by either configuring indexes or defining indexes programmatically.
- Include the following namespaces in your application:
Alachisoft.NCache.ClientAlachisoft.NCache.Runtime.CachingAlachisoft.NCache.Client.Services
- Cache must be running.
- The application must be connected to cache before performing the operation.
- 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 dependency in your pom.xml file:
<dependency>
<groupId>com.alachisoft.ncache</groupId>
<artifactId>ncache-client</artifactId>
<version>x.x.x</version>
</dependency>
- Indexing for searchable objects and their attributes need to be configured first as explained in Configuring Query Indexes in Administrator's Guide.
- Install and include the following module in your application:
- Enterprise:
const ncache = require('ncache-client')
- Cache must be running.
- The application must be connected to cache before performing the operation.
- 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.
- Install the NCache Python client by executing the following command:
# Enterprise Client
pip install ncache-client
- Indexing for searchable objects and their attributes need to be configured first as explained in Configuring Query Indexes in Administrator's Guide.
- Import the NCache module in your application.
- Cache must be running.
- 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-scala-client</artifactId>
<version>x.x.x</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.scala.client.*;import com.alachisoft.ncache.scala.runtime.caching.*;
- Cache must be running.
- The application must be connected to cache before performing the operation.
- 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.
Syntax
Here's an example that retrieves ProductName and UnitsAvailable from the cache having either 10,15,20 or 25 UnitsAvailable using ExecuteReader.
try
{
// Pre-condition: Cache is already connected
// Items are already present in the cache
// Write the query with the specified criteria
// Use the Fully Qualified Name (FQN) of your own custom class
string query = "SELECT ProductName, UnitsAvailable From FQN.Product WHERE UnitsAvailable IN (10,15,20,25)";
// 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
string ProductName = reader.GetValue<string>(1);
int UnitsAvailable = reader.GetValue<int>(2);
}
}
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
// Write the query with the specified criteria
// Use the Fully Qualified Name (FQN) of your own custom class
String query = "SELECT productName, UnitsInStock From FQN.Product WHERE UnitsInStock IN (10,15,20,25)";
// 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
String ProductName = reader.getValue(1, Product.class);
int UnitsAvailable = reader.getValue(2, 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
// Write the query with the specified criteria
// Use the Fully Qualified Name (FQN) of your own custom class
var query = "SELECT productName, UnitsInStock From FQN.Product WHERE UnitsInStock IN (10,15,20,25)";
// 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 ProductName = reader.getValue(1, Number());
var UnitsAvailable = reader.getValue(2, Number());
}
}
else
{
// Null query result set retrieved
}
}
catch (error)
{
// Handle errors
}
try:
# Pre-condition: Cache is already connected
# Items are already present in the cache
# Create a query which will be executed on the data set
query = "SELECT product_name, units_in_stock From FQN.Product WHERE units_in_stock IN (10,15,20,25)"
# Use QueryCommand for query execution
query_command = ncache.QueryCommand(query)
# Executing query command through CacheReader
search_service = cache.get_search_service()
reader = search_service.execute_reader(query_command)
# Check if result set is not empty
if reader.get_field_count() > 0:
while reader.read():
product_name = reader.get_value(str, 1)
units_available = reader.get_value(int, 2)
# Perform operations
print("Name: " + str(product_name))
print("Units: " + str(units_available))
else:
# None query results retrieved
print("Query result is None")
except Exception as exp:
# Handle errors
try {
// Pre-condition: Cache is already connected// 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
val query = "SELECT productName, UnitsInStock From FQN.Product WHERE UnitsInStock IN (10,15,20,25)"
// Use QueryCommand for query execution
val queryCommand = new QueryCommand(query)
// Executing QueryCommand through CacheReader
val 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
val ProductName = reader.getValue(1, classOf[String])
val UnitsAvailable = reader.getValue(2, classOf[Int])
}
else {
// Null query result set retrieved
}
}
catch {
case exception: Exception => {
// Handle any errors
}
}
Additional Resources
NCache provides sample application for SQL Searching on GitHub.
See Also
Locking Data For Concurrency Control
SQL Search for Keys Syntax and Usage
SQL Search for Keys Syntax and Usage
SQL Like Operator Syntax and Usage
SQL GROUP BY Syntax and Usage
Query Operators
Search Cache with LINQ