Standard query — An SQL query that you write in your EPL code. This is typically a simple query provided as a string when your EPL code initializes the query. The query string is used when the query is submitted to the database when your EPL code calls the action that starts the query. See Executing standard queries.

Prepared query — An SQL query that uses a prepared statement or stored procedure, both of which are stored in the database. Because they are stored in the database, prepared queries are more efficient than standard and named queries as they do not need to be compiled and destroyed each time they are run. Input parameters for prepared queries are not set during initialization. They are set after initialization, but before the query is submitted to the database when the query start action is called. See Prepared statements and Stored procedures.

Named query — An SQL query that you write in an XML file as part of the Apama Studio project. Typically, you use a named query if you plan to use the query multiple times (as a template, supplying parameterized values). If the query is relatively complex, it is useful to separate it from your EPL code for readability. Your EPL code specifies the query template name and the template parameter names and values to use when it initializes the query. The template name and parameters are used when the query is submitted to the database when your EPL code calls the action that starts the query. See Named queries.