executeQuery

Execute an SQL select statement.

For an overview see page McoSqlEngine

Prototypes

 
    ResultSet* SqlEngine::executeQuery(char const* sql, ...);
     
    ResultSet* SqlEngine::executeQuery(Transaction* trans, char const* sql, ...)
 

Arguments

trans	A Transaction instance. When passed, no implicit database transaction is started or committed. When absent, the SQL select statement is executed within an implicit database transaction.
sql	A string containing an SQL select statement with possible parameters to be substituted from the variable list
...	A variable length list of parameters to be substituted into the sql string

Description

These methods execute an SQL select statement with a variable list of parameters. (See page Parameter Substitution Format Specifiers). It returns a QueryResult containing the set of table rows that satisfy the query. The first version of executeQuery() starts an implicit read-only database transaction and rolls back the transaction when finished. When the second version of executeQuery(), (with the trans parameter) is called, the query is executed within the context of this Transaction; the calling application code is responsible for starting and committing or rolling back the Transaction.

Returns

This method returns a QueryResult or throws a RuntimeException in the case of an error.

Example

     
    const char * dbname = "SqlDb";
     
    int main(int argc, char* argv[])
    {
        McoSqlEngine engine;
        ...
        engine.open(db_name,  // database name
                SqlDb_get_dictionary(),  // database dictionary
                DATABASE_SIZE,  // database size
                MEMORY_PAGE_SIZE,  // page size
                MAP_ADDRESS); // mapping address for shared memory mode
        ...
        QueryResult result(engine.executeQuery("select * from Person order by age"));
        ...
    }