draxu26480 2011-06-08 19:44
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如何在不执行的情况下获取Pear MDB2生成的SQL?

I'm working with Pear MDB2 with PHP 5.3. I'm coding a project that updates a DB and before I let it start changing data, I'd like to see what the SQL queries generated by autoPrepare() and execute() look like before actually executing them.

I plan to create and execute an update query like this:

    $stmt = $db->extended->autoPrepare($tableName, $tableColumns,
    MDB2_AUTOQUERY_UPDATE, 'id = ' . $db->quote(12345, 'integer'),
    $tableColumnTypes));

    $res =& $stmt->execute($tableColumnValues);

I already know that I can see the SQL generated by autoPrepare() with placeholders for the values by accessing $stmt->query. I'd like to see the completed SQL generated by execute(), with values substituted for placeholders, without actually sending the query to the DB.

How can I do that?

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  • douliao7354 2011-06-08 19:54
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    Prepared statements are compiled on the server-side, so you can't see them before they execute. Per example, in MySQL, if you want to execute a prepared statement, what MDB2 actually does is:

    PREPARE stmt FROM 'SELECT * FROM foo WHERE bar = ?';
    SET @baz = 'baz';
    EXECUTE stmt USING @baz;
    

    The server never "returns" the actual query it executed. If you want to see what query was executed, you'll have to set-up a query log.

    Per example, in MySQL (my.cnf):

    [mysqld]
    general_log_file = /var/log/mysql_queries.log
    general_log = 1
    

    The query log would show, for the query example above:

    Query     PREPARE stmt FROM 'SELECT * FROM foo WHERE bar = ?';
    Query     SET @baz = 'baz';
    Query     EXECUTE stmt USING @baz;
    Execute   SELECT * FROM foo WHERE bar = 'baz';
    
    本回答被题主选为最佳回答 , 对您是否有帮助呢?
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