MDB2: Common functions summary
Blogs20112011-09-10
As PEAR’s core libary, MDB2 has hundreds of functions. Sometimes easily to be confused. e.g, queryOne(), fetchOne(), getOne(), they seem to be very similiar. How to distinguish them, and when to use them?
PHP Pear’s MDB2 has not much documents and examples, here I list 2 are very useful references:
I also extract and summarize the functions which are most often used, easy confusion:
1. querying
| function | describe |
|---|---|
| query | in file MDB2.php, method MDB2_Driver_Common::query() |
| Send a query to the database and return any results | |
| queryAll | in file MDB2.php, method MDB2_Driver_Common::queryAll() |
| Execute the specified query, fetch all the rows of the result set into a two dimensional array and then frees the result set. | |
| queryRow | in file MDB2.php, method MDB2_Driver_Common::queryRow() |
| Execute the specified query, fetch the values from the first row of the result set into an array and then frees the result set. | |
| queryCol | in file MDB2.php, method MDB2_Driver_Common::queryCol() |
| Execute the specified query, fetch the value from the first column of each row of the result set into an array and then frees the result set. | |
| queryOne | in file MDB2.php, method MDB2_Driver_Common::queryOne() |
| Execute the specified query, fetch the value from the first column of the first row of the result set and then frees the result set. |
2. results
| function | describe |
|---|---|
| fetchAll | in file MDB2.php, method MDB2_Result_Common::fetchAll() |
| Fetch and return all rows from the current row pointer position | |
| fetchRow | in file MDB2.php, method MDB2_Result_Common::fetchRow() |
| Fetch and return a row of data | |
| fetchCol | in file MDB2.php, method MDB2_Result_Common::fetchCol() |
| Fetch and return a column from the current row pointer position | |
| fetchOne | in file MDB2.php, method MDB2_Result_Common::fetchOne() |
| fetch single column from the next row from a result set |
3. gets
| function | describe |
|---|---|
| getAll | in file Extended.php, method MDB2_Extended::getAll() |
| Fetch all the rows returned from a query. | |
| getRow | in file Extended.php, method MDB2_Extended::getRow() |
| Fetch the first row of data returned from a query. Takes care of doing the query and freeing the results when finished. | |
| getCol | in file Extended.php, method MDB2_Extended::getCol() |
| Fetch a single column from a result set and return it as an indexed array. | |
| getOne | in file Extended.php, method MDB2_Extended::getOne() |
| Fetch the first column of the first row of data returned from a query. | |
| getColumnNames | in file MDB2.php, method MDB2_Result_Common::getColumnNames() |
| Retrieve the names of columns returned by the DBMS in a query result or from the cache. |
4. misc
| function | describe |
|---|---|
| numCols | in file MDB2.php, method MDB2_Result_Common::numCols() |
| Count the number of columns returned by the DBMS in a query result. | |
| numRows | in file MDB2.php, method MDB2_Result_Common::numRows() |
| Returns the number of rows in a result object | |
| escape | in file MDB2.php, method MDB2_Driver_Common::escape() |
| Quotes a string so it can be safely used in a query. It will quote the text so it can safely be used within a query. | |
| exec | in file MDB2.php, method MDB2_Driver_Common::exec() |
| Execute a manipulation query to the database and return the number of affected rows | |
| rowCount | in file MDB2.php, method MDB2_Result_Common::rowCount() |
| Returns the actual row number that was last fetched (count from 0), used in CRUD. | |
| lastInsertID | in file MDB2.php, method MDB2_Driver_Common::lastInsertID() |
| Returns the autoincrement ID if supported or $id or fetches the current ID in a sequence called: $table.(empty($field) ? ” : ’_’.$field) | |
| isError | in file MDB2.php, method MDB2::isError() |
| Tell whether a value is a MDB2 error. |