12/31/2023 0 Comments Mariadb stored procedure![]() The simplest way to retrieve the data in this case is to use a getString method on the ResultSet, passing the name of the variable to access. This query results in a ResultSet that can then be processed in a while loop. To obtain the output parameter, an additional query must be executed. First, the CALL is executed as seen earlier. If running the SQL statements directly, this might be similar to the following:ĬALL the C++ code, a similar sequence is carried out. This is not returned as such, but needs to be obtained using a query. In this scenario, the stored procedure sets an output parameter. Note the output generated by the program. Stmt->execute('CALL get_pop(\'Uganda\', res(stmt->executeQuery('SELECT AS _reply')) Ĭout getString('_reply') execute('CALL get_pop_continent(\'Asia\', AS _reply')) Ĭout getString('_reply') execute('CALL AS _reply')) Ĭout getString('_reply') g++ -o sp_scenario2 -I/usr/local/include/cppconn/ -lmysqlcppconn sp_scenario2.cpp Std::auto_ptr con(driver->connect(url, user, pass)) Sql::Driver* driver = get_driver_instance() Enter the following code into the tutorial framework code:.You will now see how to handle a stored procedure that returns an output parameter. Scenario 2 - Stored procedure returns an output parameter If the call fails for some reason, an exception will be raised, and this will be handled by the catch statement in the code. MariaDB Connector/C++ handles this status for you, so you do not need code to handle it explicitly. The stored procedure itself does not return a value, although it is important to note there will always be a return value from the call - this is simply the call status. The code in this case simply creates a statement and then invokes the execute method on it, passing the call to the stored procedure as a parameter. ![]() SELECT Code, Name, Continent FROM Country WHERE Code='ATL' Using the mysql Command Line Client, or other suitable tool, check the World database to determine that it has been updated correctly.Shell> g++ -o sp_scenario1 -I/usr/local/include/cppconn/ -lmysqlcppconn sp_scenario1.cpp Compile the program using the following command:.Stmt->execute('CALL add_country(\'ATL\', \'Atlantis\', \'North America\')') an error Connector/C++ will generate an exception. We don't need to check the return value explicitly, if it indicates Std::auto_ptr stmt(con->createStatement()) SELECT Code, Name, Population, Continent FROM Country WHERE Continent = 'Oceania' AND Population con(driver->connect(url, user, pass)) This routine corresponds to Scenario 3 above. The next routine is an example of a procedure returning a result set containing multiple records. SELECT Population INTO country_pop FROM Country WHERE Name = country_name The next routine returns the population of a specified country, and corresponds to Scenario 2 above:ĬREATE PROCEDURE get_pop (IN country_name CHAR(52), OUT country_pop INT(11)) INSERT INTO Country(Code, Name, Continent) VALUES (country_code, country_name, continent_name) This corresponds to Scenario 1 above.ĬREATE PROCEDURE add_country (IN country_code CHAR(3), IN country_name CHAR(52), IN continent_name CHAR(30)) The following routine adds a country into the World database, but does not return a result. The following stored procedures illustrate each of these scenarios. Your application loops through the result set to display, transform, or otherwise process each item. The procedure can execute a query that matches an arbitrary number of table rows. A stored procedure that returns a result set.For example, such a procedure can indicate success or failure, query a single item of data, or combine multiple data items into a single result. A stored procedure that returns an output parameter.For example, such a stored procedure can log non-critical information, or change database data in a straightforward way. A stored procedure that does not return any result. ![]() You can construct and call various combinations of stored procedures: The following tutorial, "Tutorial: Calling Stored Procedures with Prepared Statements in MariaDB Connector/C++" will cover the use of Prepared Statements. ![]() This tutorial looks at calling stored procedures using Statements. Stored procedures can be called using both Statements and Prepared Statements.
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