Differences between PHPPDOStatement objects bindpram (), bindvalue (), and bindcolumn

This article describes the differences between the PHPPDOStatement object bindpram (), bindvalue (), and bindcolumn. For more information, see

This article mainly introduces the differences between PHP PDOStatement object bindpram (), bindvalue () and bindcolumn. For more information, see

PDOStatement: bindParam-bind a parameter to the specified variable name.

Bind a PHP variable to the corresponding name placeholder or question mark placeholder in the SQL statement used for preprocessing. Unlike PDOStatement: bindValue (), this variable is bound as a reference and takes its value only when PDOStatement: execute () is called.

PDOStatement: bindValue-binds a value to a parameter.

Bind a value to the corresponding name placeholder or question mark placeholder in the SQL statement used for preprocessing.

The Code is as follows:

<? Php
$ Stm = $ pdo-> prepare ("select * from users where user =: user ");
$ User = "jack ";
// Correct
$ Stm-> bindParam (": user", $ user );
// Error
$ Stm-> bindParam (": user", "jack ");
// Correct
$ Stm-> bindValue (": user", $ user );
// Correct
$ Stm-> bindValue (": user", "jack ");

// Therefore, bindParam is the second parameter. Only the variable name can be used, but not the variable value. bindValue can use the specific value.
?>

PDOStatement: bindColumn-bind a column to a PHP variable.

Bind a specific variable to a specified column in a query result set. Every call to PDOStatement: fetch () or PDOStatement: fetchAll () will update all the variables bound to the column.

The Code is as follows:

<? Php
Function readData ($ dbh ){
$ SQL = 'select name, color, calories FROM fruit ';
Try {
$ Stmt = $ dbh-> prepare ($ SQL );
$ Stmt-> execute ();

/* Bind the column number */
$ Stmt-> bindColumn (1, $ name );
$ Stmt-> bindColumn (2, $ color );

/* Bind by column name */
$ Stmt-> bindColumn ('calories ', $ cals );

While ($ row = $ stmt-> fetch (PDO: FETCH_BOUND )){
$ Data = $ name. "\ t". $ color. "\ t". $ cals. "\ n ";
Print $ data;
}
}
Catch (PDOException $ e ){
Print $ e-> getMessage ();
}
}
ReadData ($ dbh );
?>

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