Statements

Bind parameters and run prepared SQL. More...

Classes
class	Statement
	Prepared SQL statement with named host variables. More...

Detailed Description

Statement is a compiled query with named host variables. Obtain one from Connection::prepare() or Connection::prepareCached(). It is a shared value: copying is cheap, and the backend lives until the last wrapper is destroyed. An unbound statement is empty; operator!() is true for that state.

A host variable is a colon, then a name that starts with a letter and continues with letters, digits or underscore, for example :id. Names are not scanned inside strings delimited by apostrophes, quotation marks or backticks. A backslash prevents the next character from being special. set() binds a name to a typed value. setNull() binds a name to SQL NULL. clear() sets every host variable to NULL.

execute() runs a statement that does not return rows, typically INSERT, UPDATE or DELETE, and returns how many rows changed. lastInsertId() is the generated row id after that execute. select() runs a query and returns a fully buffered Result. selectRow() returns the first row and discards the rest; it throws InvalidQuery when the query returns no row. selectValue() returns the first column of the first row, with the same empty-result error.

For a result that should not be fully buffered, getCursor() opens a batch Cursor on this statement. Cursor use is documented with that type.

Asynchronous execute and select follow the connection model: beginExecute() / endExecute() / executeFinished(), and beginSelect() / endSelect() / selectFinished(). cancel() aborts a pending operation on this statement. The connection must have been attached with setActive() first.

Pt::Db::Statement stmt = conn.prepare(
    "INSERT INTO users(name) VALUES(:name)");
stmt.set("name", std::string("Ada"));
stmt.execute();
long long id = stmt.lastInsertId();