How to prepare sql statements and bind parameters? - c++

Question

Unfortunatelly, the documentation completely lacks examples (what is really strange), as if it assumes all its readers to be good programmers. Whereas, I'm quite new to C++ and can not really figure out from the documentation how to really prepare and execute statements. I love the way how it is implemented in PDO for PHP. Normally, I just do it like this:
$s = $db->prepare("SELECT id FROM mytable WHERE id = :id");
$s->bindParam(':id', $id);
$s->execute();
or do it using ? tokens:
$data = array();
$data[] = 1;
$data[] = 2;
$s = $db->prepare("SELECT id FROM mytable WHERE id = ? or id = ?");
$s->execute($data);
Now, I have C++ and sqlite3.h in my hands. At this moment, I know just how to connect to database - I do it and get no errors:
sqlite3 * conn;
int rc = sqlite3_open(db_name, &conn);
Please, give some instructions (with clear tiny examples) about how to implement similar things that PDO does in PHP - prepare a statement using named arguments and using ? tokens.

Answer 1

You can find a decent amount of documentation here: sqlite.org
This example does not explain the sqlite3 function calls and parameters in detail, as that is quite a lot of information to cover - instead refer to the given link for more in-depth detail.
This example binds values to the statement in your question multiple times, and reads all query results after each bind:
sqlite3* conn;
sqlite3_stmt* stmt = 0;
int rc = sqlite3_open(db_name, &conn);
// Good idea to always check the return value of sqlite3 function calls.
// Only done once in this example:
if ( rc != SQLITE_OK ) { // Do something }
rc = sqlite3_prepare_v2( conn, "SELECT id FROM myTable WHERE id = ? or id = ?", -1, &stmt, 0 );
// Optional, but will most likely increase performance.
rc = sqlite3_exec( conn, "BEGIN TRANSACTION", 0, 0, 0 );
for ( int bindIndex = 0; bindIndex < number_of_times_you_wish_to_bind; bindIndex++ ) {
// Binding integer values in this example.
// Bind functions for other data-types are available - see end of post.
// Bind-parameter indexing is 1-based.
rc = sqlite3_bind_int( stmt, 1, int_you_wish_to_bind ); // Bind first parameter.
rc = sqlite3_bind_int( stmt, 2, int_you_wish_to_bind ); // Bind second parameter.
// Reading interger results in this example.
// Read functions for other data-types are available - see end of post.
while ( sqlite3_step( stmt ) == SQLITE_ROW ) { // While query has result-rows.
// In your example the column count will be 1.
for ( int colIndex = 0; colIndex < sqlite3_column_count( stmt ); colIndex++ ) {
int result = sqlite3_column_int( stmt, colIndex );
// Do something with the result.
}
}
// Step, Clear and Reset the statement after each bind.
rc = sqlite3_step( stmt );
rc = sqlite3_clear_bindings( stmt );
rc = sqlite3_reset( stmt );
}
char *zErrMsg = 0; // Can perhaps display the error message if rc != SQLITE_OK.
rc = sqlite3_exec( conn, "END TRANSACTION", 0, 0, &zErrMsg ); // End the transaction.
rc = sqlite3_finalize( stmt ); // Finalize the prepared statement.
More Bind Functions
More Read Functions

Answer 2

As I understand from http://hoogli.com/items/Avoid_sqlite3_clear_bindings().html, the step rc = sqlite3_clear_bindings( stmt ); is not necessary in this case.
Unfortunately, I am not yet allowed to post this as a comment to the very good previous answer.