Preparing and Executing Statements

Creating a Statement

The cppdb::statement objects are usually created by calling cppdb::session::prepare() function or by using cppdb::session::operator<<(). Prepare statements are usually cached for future reuse. Non-prepared statements can be also created by calling cppdb::session::create_statement() and prepared statements can be created without caching by calling cppdb::session::create_prepared_uncached_statement(). It is useful when such statements are rarely executed or executed only once.

For example:

cppdb::statement st=sql.prepare("DELETE FROM users");

Binding Parameters

The statement may contain placeholders marked with "?" for parameters that should be binded. The values for placeholders can be binded by their order using cppdb::statement::operator<<() or bind() functions. The placeholder order can be also specified explicitly starting from 1.

For example:

cppdb::statement st=sql.prepare("DELETE FROM users WHERE age<? AND role<>?");

Of course syntactic sugar may be used as well:

cppdb::statement st=sql << "DELETE FROM users WHERE age<? AND role<>?" << 13 << "moderator";

Binding NULL values.

Executing Statements

Statements are executed by calling cppdb::statement::exec(). Also manipulator cppdb::exec provided for execution of a statement that allows writing complex queries in one line.

sql << "DELETE FROM users WHERE age<? AND role<>?" << 13 << "moderator" <<cppdb::exec;

Fetching Meta-data

Meta-data about recently executed statement can fetched using following functions:

Reusing Statement

The same prepared statement can be reused multiple times. For this purpose after each call of ppdb::statement::exec() or ppdb::statement::query(), ppdb::statement::reset() should be called that would clear all bindings and allow executing it once again:

cppdb::statement st = sql << "INSERT INTO students(id,name) values(?,?)";
for(i=0;i<students.size();i++) {
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