This quick start guide will help with choosing and gaining familiarity with the PHP MySQL API. This quick start gives an overview on the mysqli extension. Code examples are provided for all major aspects of the API. Database concepts are explained to the degree needed for presenting concepts specific to MySQL. Required: A familiarity with the PHP programming language, the SQL language, and basic knowledge of the MySQL server.

The mysqli extension features a dual interface. It supports the procedural and object-oriented programming paradigm. Users migrating from the old mysql extension may prefer the procedural interface. The procedural interface is similar to that of the old mysql extension. In many cases, the function names differ only by prefix. Some mysqli functions take a connection handle as their first argument, whereas matching functions in the old mysql interface take it as an optional last argument. &example.outputs; The object-oriented interface In addition to the classical procedural interface, users can choose to use the object-oriented interface. The documentation is organized using the object-oriented interface. The object-oriented interface shows functions grouped by their purpose, making it easier to get started. The reference section gives examples for both syntax variants. There are no significant performance differences between the two interfaces. Users can base their choice on personal preference. query("SELECT 'choices to please everybody.' AS _msg FROM DUAL"); $row = $result->fetch_assoc(); echo $row['_msg']; ]]> &example.outputs; The object-oriented interface is used for the quickstart because the reference section is organized that way. Mixing styles It is possible to switch between styles at any time. Mixing both styles is not recommended for code clarity and coding style reasons. fetch_assoc()) { echo $row['_msg']; } ]]> &example.outputs; See also mysqli::__construct mysqli::query mysqli_result::fetch_assoc $mysqli::connect_errno $mysqli::connect_error $mysqli::errno $mysqli::error The MySQLi Extension Function Summary

The MySQL server supports the use of different transport layers for connections. Connections use TCP/IP, Unix domain sockets or Windows named pipes. The hostname localhost has a special meaning. It is bound to the use of Unix domain sockets. To open a TCP/IP connection to the localhost, 127.0.0.1 must be used instead of the hostname localhost. host_info . "\n"; $mysqli = new mysqli("127.0.0.1", "user", "password", "database", 3306); echo $mysqli->host_info . "\n"; ]]> &example.outputs; Connection parameter defaults Depending on the connection function used, assorted parameters can be omitted. If a parameter is not provided, then the extension attempts to use the default values that are set in the PHP configuration file. The resulting parameter values are then passed to the client library that is used by the extension. If the client library detects empty or unset parameters, then it may default to the library built-in values. Built-in connection library defaults If the host value is unset or empty, then the client library will default to a Unix socket connection on localhost. If socket is unset or empty, and a Unix socket connection is requested, then a connection to the default socket on /tmp/mysql.sock is attempted. On Windows systems, the host name . is interpreted by the client library as an attempt to open a Windows named pipe based connection. In this case the socket parameter is interpreted as the pipe name. If not given or empty, then the socket (pipe name) defaults to \\.\pipe\MySQL. If neither a Unix domain socket based not a Windows named pipe based connection is to be established and the port parameter value is unset, the library will default to port 3306. The mysqlnd library and the MySQL Client Library (libmysqlclient) implement the same logic for determining defaults. Connection options Connection options are available to, for example, set init commands which are executed upon connect, or for requesting use of a certain charset. Connection options must be set before a network connection is established. For setting a connection option, the connect operation has to be performed in three steps: creating a connection handle with mysqli_init or mysqli::__construct, setting the requested options using mysqli::options, and establishing the network connection with mysqli::real_connect. Connection pooling The mysqli extension supports persistent database connections, which are a special kind of pooled connections. By default, every database connection opened by a script is either explicitly closed by the user during runtime or released automatically at the end of the script. A persistent connection is not. Instead it is put into a pool for later reuse, if a connection to the same server using the same username, password, socket, port and default database is opened. Reuse saves connection overhead. Every PHP process is using its own mysqli connection pool. Depending on the web server deployment model, a PHP process may serve one or multiple requests. Therefore, a pooled connection may be used by one or more scripts subsequently. Persistent connection If an unused persistent connection for a given combination of host, username, password, socket, port and default database cannot be found in the connection pool, then mysqli opens a new connection. The use of persistent connections can be enabled and disabled using the PHP directive mysqli.allow_persistent. The total number of connections opened by a script can be limited with mysqli.max_links. The maximum number of persistent connections per PHP process can be restricted with mysqli.max_persistent. Please note that the web server may spawn many PHP processes. A common complain about persistent connections is that their state is not reset before reuse. For example, open and unfinished transactions are not automatically rolled back. But also, authorization changes which happened in the time between putting the connection into the pool and reusing it are not reflected. This may be seen as an unwanted side-effect. On the contrary, the name persistent may be understood as a promise that the state is persisted. The mysqli extension supports both interpretations of a persistent connection: state persisted, and state reset before reuse. The default is reset. Before a persistent connection is reused, the mysqli extension implicitly calls mysqli::change_user to reset the state. The persistent connection appears to the user as if it was just opened. No artifacts from previous usages are visible. The mysqli::change_user call is an expensive operation. For best performance, users may want to recompile the extension with the compile flag MYSQLI_NO_CHANGE_USER_ON_PCONNECT being set. It is left to the user to choose between safe behavior and best performance. Both are valid optimization goals. For ease of use, the safe behavior has been made the default at the expense of maximum performance. See also mysqli::__construct mysqli_init mysqli::options mysqli::real_connect mysqli::change_user $mysqli::host_info MySQLi Configuration Options Persistent Database Connections

Statements can be executed with the mysqli::query, mysqli::real_query and mysqli::multi_query. The mysqli::query function is the most common, and combines the executing statement with a buffered fetch of its result set, if any, in one call. Calling mysqli::query is identical to calling mysqli::real_query followed by mysqli::store_result. query("DROP TABLE IF EXISTS test"); $mysqli->query("CREATE TABLE test(id INT)"); ]]> Buffered result sets After statement execution, results can be either retrieved all at once or read row by row from the server. Client-side result set buffering allows the server to free resources associated with the statement's results as early as possible. Generally speaking, clients are slow consuming result sets. Therefore, it is recommended to use buffered result sets. mysqli::query combines statement execution and result set buffering. PHP applications can navigate freely through buffered results. Navigation is fast because the result sets are held in client memory. Please, keep in mind that it is often easier to scale by client than it is to scale the server. query("DROP TABLE IF EXISTS test"); $mysqli->query("CREATE TABLE test(id INT)"); $mysqli->query("INSERT INTO test(id) VALUES (1), (2), (3)"); $result = $mysqli->query("SELECT id FROM test ORDER BY id ASC"); echo "Reverse order...\n"; for ($row_no = $result->num_rows - 1; $row_no >= 0; $row_no--) { $result->data_seek($row_no); $row = $result->fetch_assoc(); echo " id = " . $row['id'] . "\n"; } echo "Result set order...\n"; foreach ($result as $row) { echo " id = " . $row['id'] . "\n"; } ]]> &example.outputs; Unbuffered result sets If client memory is a short resource and freeing server resources as early as possible to keep server load low is not needed, unbuffered results can be used. Scrolling through unbuffered results is not possible before all rows have been read. real_query("SELECT id FROM test ORDER BY id ASC"); $result = $mysqli->use_result(); echo "Result set order...\n"; foreach ($result as $row) { echo " id = " . $row['id'] . "\n"; } ]]> Result set values data types The mysqli::query, mysqli::real_query and mysqli::multi_query functions are used to execute non-prepared statements. At the level of the MySQL Client Server Protocol, the command COM_QUERY and the text protocol are used for statement execution. With the text protocol, the MySQL server converts all data of a result sets into strings before sending. This conversion is done regardless of the SQL result set column data type. The mysql client libraries receive all column values as strings. No further client-side casting is done to convert columns back to their native types. Instead, all values are provided as PHP strings. query("DROP TABLE IF EXISTS test"); $mysqli->query("CREATE TABLE test(id INT, label CHAR(1))"); $mysqli->query("INSERT INTO test(id, label) VALUES (1, 'a')"); $result = $mysqli->query("SELECT id, label FROM test WHERE id = 1"); $row = $result->fetch_assoc(); printf("id = %s (%s)\n", $row['id'], gettype($row['id'])); printf("label = %s (%s)\n", $row['label'], gettype($row['label'])); ]]> &example.outputs; It is possible to convert integer and float columns back to PHP numbers by setting the MYSQLI_OPT_INT_AND_FLOAT_NATIVE connection option, if using the mysqlnd library. If set, the mysqlnd library will check the result set meta data column types and convert numeric SQL columns to PHP numbers, if the PHP data type value range allows for it. This way, for example, SQL INT columns are returned as integers. options(MYSQLI_OPT_INT_AND_FLOAT_NATIVE, 1); $mysqli->real_connect("example.com", "user", "password", "database"); $mysqli->query("DROP TABLE IF EXISTS test"); $mysqli->query("CREATE TABLE test(id INT, label CHAR(1))"); $mysqli->query("INSERT INTO test(id, label) VALUES (1, 'a')"); $result = $mysqli->query("SELECT id, label FROM test WHERE id = 1"); $row = $result->fetch_assoc(); printf("id = %s (%s)\n", $row['id'], gettype($row['id'])); printf("label = %s (%s)\n", $row['label'], gettype($row['label'])); ]]> &example.outputs; See also mysqli::__construct mysqli::options mysqli::real_connect mysqli::query mysqli::multi_query mysqli::use_result mysqli::store_result

The MySQL database supports prepared statements. A prepared statement or a parameterized statement is used to execute the same statement repeatedly with high efficiency and protect against SQL injections. Basic workflow The prepared statement execution consists of two stages: prepare and execute. At the prepare stage a statement template is sent to the database server. The server performs a syntax check and initializes server internal resources for later use. The MySQL server supports using anonymous, positional placeholder with ?. Prepare is followed by execute. During execute the client binds parameter values and sends them to the server. The server executes the statement with the bound values using the previously created internal resources. query("DROP TABLE IF EXISTS test"); $mysqli->query("CREATE TABLE test(id INT, label TEXT)"); /* Prepared statement, stage 1: prepare */ $stmt = $mysqli->prepare("INSERT INTO test(id, label) VALUES (?, ?)"); /* Prepared statement, stage 2: bind and execute */ $id = 1; $label = 'PHP'; $stmt->bind_param("is", $id, $label); // "is" means that $id is bound as an integer and $label as a string $stmt->execute(); ]]> Repeated execution A prepared statement can be executed repeatedly. Upon every execution the current value of the bound variable is evaluated and sent to the server. The statement is not parsed again. The statement template is not transferred to the server again. query("DROP TABLE IF EXISTS test"); $mysqli->query("CREATE TABLE test(id INT, label TEXT)"); /* Prepared statement, stage 1: prepare */ $stmt = $mysqli->prepare("INSERT INTO test(id, label) VALUES (?, ?)"); /* Prepared statement, stage 2: bind and execute */ $stmt->bind_param("is", $id, $label); // "is" means that $id is bound as an integer and $label as a string $data = [ 1 => 'PHP', 2 => 'Java', 3 => 'C++' ]; foreach ($data as $id => $label) { $stmt->execute(); } $result = $mysqli->query('SELECT id, label FROM test'); var_dump($result->fetch_all(MYSQLI_ASSOC)); ]]> &example.outputs; array(2) { ["id"]=> string(1) "1" ["label"]=> string(3) "PHP" } [1]=> array(2) { ["id"]=> string(1) "2" ["label"]=> string(4) "Java" } [2]=> array(2) { ["id"]=> string(1) "3" ["label"]=> string(3) "C++" } } ]]> Every prepared statement occupies server resources. Statements should be closed explicitly immediately after use. If not done explicitly, the statement will be closed when the statement handle is freed by PHP. Using a prepared statement is not always the most efficient way of executing a statement. A prepared statement executed only once causes more client-server round-trips than a non-prepared statement. This is why the SELECT is not run as a prepared statement above. Also, consider the use of the MySQL multi-INSERT SQL syntax for INSERTs. For the example, multi-INSERT requires fewer round-trips between the server and client than the prepared statement shown above. query("DROP TABLE IF EXISTS test"); $mysqli->query("CREATE TABLE test(id INT)"); $values = [1, 2, 3, 4]; $stmt = $mysqli->prepare("INSERT INTO test(id) VALUES (?), (?), (?), (?)"); $stmt->bind_param('iiii', ...$values); $stmt->execute(); ]]> Result set values data types The MySQL Client Server Protocol defines a different data transfer protocol for prepared statements and non-prepared statements. Prepared statements are using the so called binary protocol. The MySQL server sends result set data "as is" in binary format. Results are not serialized into strings before sending. Client libraries receive binary data and try to convert the values into appropriate PHP data types. For example, results from an SQL INT column will be provided as PHP integer variables. query("DROP TABLE IF EXISTS test"); $mysqli->query("CREATE TABLE test(id INT, label TEXT)"); $mysqli->query("INSERT INTO test(id, label) VALUES (1, 'PHP')"); $stmt = $mysqli->prepare("SELECT id, label FROM test WHERE id = 1"); $stmt->execute(); $result = $stmt->get_result(); $row = $result->fetch_assoc(); printf("id = %s (%s)\n", $row['id'], gettype($row['id'])); printf("label = %s (%s)\n", $row['label'], gettype($row['label'])); ]]> &example.outputs; This behavior differs from non-prepared statements. By default, non-prepared statements return all results as strings. This default can be changed using a connection option. If the connection option is used, there are no differences. Fetching results using bound variables Results from prepared statements can either be retrieved by binding output variables, or by requesting a mysqli_result object. Output variables must be bound after statement execution. One variable must be bound for every column of the statements result set. query("DROP TABLE IF EXISTS test"); $mysqli->query("CREATE TABLE test(id INT, label TEXT)"); $mysqli->query("INSERT INTO test(id, label) VALUES (1, 'PHP')"); $stmt = $mysqli->prepare("SELECT id, label FROM test WHERE id = 1"); $stmt->execute(); $stmt->bind_result($out_id, $out_label); while ($stmt->fetch()) { printf("id = %s (%s), label = %s (%s)\n", $out_id, gettype($out_id), $out_label, gettype($out_label)); } ]]> &example.outputs; Prepared statements return unbuffered result sets by default. The results of the statement are not implicitly fetched and transferred from the server to the client for client-side buffering. The result set takes server resources until all results have been fetched by the client. Thus it is recommended to consume results timely. If a client fails to fetch all results or the client closes the statement before having fetched all data, the data has to be fetched implicitly by mysqli. It is also possible to buffer the results of a prepared statement using mysqli_stmt::store_result. Fetching results using mysqli_result interface Instead of using bound results, results can also be retrieved through the mysqli_result interface. mysqli_stmt::get_result returns a buffered result set. query("DROP TABLE IF EXISTS test"); $mysqli->query("CREATE TABLE test(id INT, label TEXT)"); $mysqli->query("INSERT INTO test(id, label) VALUES (1, 'PHP')"); $stmt = $mysqli->prepare("SELECT id, label FROM test WHERE id = 1"); $stmt->execute(); $result = $stmt->get_result(); var_dump($result->fetch_all(MYSQLI_ASSOC)); ]]> &example.outputs; array(2) { ["id"]=> int(1) ["label"]=> string(3) "PHP" } } ]]> Using the mysqli_result interface offers the additional benefit of flexible client-side result set navigation. query("DROP TABLE IF EXISTS test"); $mysqli->query("CREATE TABLE test(id INT, label TEXT)"); $mysqli->query("INSERT INTO test(id, label) VALUES (1, 'PHP'), (2, 'Java'), (3, 'C++')"); $stmt = $mysqli->prepare("SELECT id, label FROM test"); $stmt->execute(); $result = $stmt->get_result(); for ($row_no = $result->num_rows - 1; $row_no >= 0; $row_no--) { $result->data_seek($row_no); var_dump($result->fetch_assoc()); } ]]> &example.outputs; int(3) ["label"]=> string(3) "C++" } array(2) { ["id"]=> int(2) ["label"]=> string(4) "Java" } array(2) { ["id"]=> int(1) ["label"]=> string(3) "PHP" } ]]> Escaping and SQL injection Bound variables are sent to the server separately from the query and thus cannot interfere with it. The server uses these values directly at the point of execution, after the statement template is parsed. Bound parameters do not need to be escaped as they are never substituted into the query string directly. A hint must be provided to the server for the type of bound variable, to create an appropriate conversion. See the mysqli_stmt::bind_param function for more information. Such a separation sometimes considered as the only security feature to prevent SQL injection, but the same degree of security can be achieved with non-prepared statements, if all the values are formatted correctly. It should be noted that correct formatting is not the same as escaping and involves more logic than simple escaping. Thus, prepared statements are simply a more convenient and less error-prone approach to this element of database security. Client-side prepared statement emulation The API does not include emulation for client-side prepared statement emulation. Quick comparison of prepared and non-prepared statements The table below compares server-side prepared and non-prepared statements. Prepared Statement Non-prepared statement Client-server round trips, SELECT, single execution 2 1 Statement string transferred from client to server 1 1 Client-server round trips, SELECT, repeated (n) execution 1 + n n Statement string transferred from client to server 1 template, n times bound parameter, if any n times and parsed every time Input parameter binding API Yes No, manual input escaping Output variable binding API Yes No Supports use of mysqli_result API Yes, use mysqli_stmt::get_result Yes Buffered result sets Yes, use mysqli_stmt::get_result or binding with mysqli_stmt::store_result Yes, default of mysqli::query Unbuffered result sets Yes, use output binding API Yes, use mysqli::real_query with mysqli::use_result MySQL Client Server protocol data transfer flavor Binary protocol Text protocol Result set values SQL data types Preserved when fetching Converted to string or preserved when fetching Supports all SQL statements Recent MySQL versions support most but not all Yes See also mysqli::__construct mysqli::query mysqli::prepare mysqli_stmt::prepare mysqli_stmt::execute mysqli_stmt::bind_param mysqli_stmt::bind_result

The MySQL database supports stored procedures. A stored procedure is a subroutine stored in the database catalog. Applications can call and execute the stored procedure. The CALL SQL statement is used to execute a stored procedure. Parameter Stored procedures can have IN, INOUT and OUT parameters, depending on the MySQL version. The mysqli interface has no special notion for the different kinds of parameters. IN parameter Input parameters are provided with the CALL statement. Please, make sure values are escaped correctly. query("DROP TABLE IF EXISTS test"); $mysqli->query("CREATE TABLE test(id INT)"); $mysqli->query("DROP PROCEDURE IF EXISTS p"); $mysqli->query("CREATE PROCEDURE p(IN id_val INT) BEGIN INSERT INTO test(id) VALUES(id_val); END;"); $mysqli->query("CALL p(1)"); $result = $mysqli->query("SELECT id FROM test"); var_dump($result->fetch_assoc()); ]]> &example.outputs; string(1) "1" } ]]> INOUT/OUT parameter The values of INOUT/OUT parameters are accessed using session variables. query("DROP PROCEDURE IF EXISTS p"); $mysqli->query('CREATE PROCEDURE p(OUT msg VARCHAR(50)) BEGIN SELECT "Hi!" INTO msg; END;'); $mysqli->query("SET @msg = ''"); $mysqli->query("CALL p(@msg)"); $result = $mysqli->query("SELECT @msg as _p_out"); $row = $result->fetch_assoc(); echo $row['_p_out']; ]]> &example.outputs; Application and framework developers may be able to provide a more convenient API using a mix of session variables and databased catalog inspection. However, please note the possible performance impact of a custom solution based on catalog inspection. Handling result sets Stored procedures can return result sets. Result sets returned from a stored procedure cannot be fetched correctly using mysqli::query. The mysqli::query function combines statement execution and fetching the first result set into a buffered result set, if any. However, there are additional stored procedure result sets hidden from the user which cause mysqli::query to fail returning the user expected result sets. Result sets returned from a stored procedure are fetched using mysqli::real_query or mysqli::multi_query. Both functions allow fetching any number of result sets returned by a statement, such as CALL. Failing to fetch all result sets returned by a stored procedure causes an error. query("DROP TABLE IF EXISTS test"); $mysqli->query("CREATE TABLE test(id INT)"); $mysqli->query("INSERT INTO test(id) VALUES (1), (2), (3)"); $mysqli->query("DROP PROCEDURE IF EXISTS p"); $mysqli->query('CREATE PROCEDURE p() READS SQL DATA BEGIN SELECT id FROM test; SELECT id + 1 FROM test; END;'); $mysqli->multi_query("CALL p()"); do { if ($result = $mysqli->store_result()) { printf("---\n"); var_dump($result->fetch_all()); $result->free(); } } while ($mysqli->next_result()); ]]> &example.outputs; array(1) { [0]=> string(1) "1" } [1]=> array(1) { [0]=> string(1) "2" } [2]=> array(1) { [0]=> string(1) "3" } } --- array(3) { [0]=> array(1) { [0]=> string(1) "2" } [1]=> array(1) { [0]=> string(1) "3" } [2]=> array(1) { [0]=> string(1) "4" } } ]]> Use of prepared statements No special handling is required when using the prepared statement interface for fetching results from the same stored procedure as above. The prepared statement and non-prepared statement interfaces are similar. Please note, that not every MYSQL server version may support preparing the CALL SQL statement. query("DROP TABLE IF EXISTS test"); $mysqli->query("CREATE TABLE test(id INT)"); $mysqli->query("INSERT INTO test(id) VALUES (1), (2), (3)"); $mysqli->query("DROP PROCEDURE IF EXISTS p"); $mysqli->query('CREATE PROCEDURE p() READS SQL DATA BEGIN SELECT id FROM test; SELECT id + 1 FROM test; END;'); $stmt = $mysqli->prepare("CALL p()"); $stmt->execute(); do { if ($result = $stmt->get_result()) { printf("---\n"); var_dump($result->fetch_all()); $result->free(); } } while ($stmt->next_result()); ]]> &example.outputs; array(1) { [0]=> int(1) } [1]=> array(1) { [0]=> int(2) } [2]=> array(1) { [0]=> int(3) } } --- array(3) { [0]=> array(1) { [0]=> int(2) } [1]=> array(1) { [0]=> int(3) } [2]=> array(1) { [0]=> int(4) } } ]]> Of course, use of the bind API for fetching is supported as well. query("DROP TABLE IF EXISTS test"); $mysqli->query("CREATE TABLE test(id INT)"); $mysqli->query("INSERT INTO test(id) VALUES (1), (2), (3)"); $mysqli->query("DROP PROCEDURE IF EXISTS p"); $mysqli->query('CREATE PROCEDURE p() READS SQL DATA BEGIN SELECT id FROM test; SELECT id + 1 FROM test; END;'); $stmt = $mysqli->prepare("CALL p()"); $stmt->execute(); do { if ($stmt->store_result()) { $stmt->bind_result($id_out); while ($stmt->fetch()) { echo "id = $id_out\n"; } } } while ($stmt->next_result()); ]]> &example.outputs; See also mysqli::query mysqli::multi_query mysqli::next_result mysqli::more_results

MySQL optionally allows having multiple statements in one statement string, but it requires special handling. Multiple statements or multi queries must be executed with mysqli::multi_query. The individual statements of the statement string are separated by semicolon. Then, all result sets returned by the executed statements must be fetched. The MySQL server allows having statements that do return result sets and statements that do not return result sets in one multiple statement. query("DROP TABLE IF EXISTS test"); $mysqli->query("CREATE TABLE test(id INT)"); $sql = "SELECT COUNT(*) AS _num FROM test; INSERT INTO test(id) VALUES (1); SELECT COUNT(*) AS _num FROM test; "; $mysqli->multi_query($sql); do { if ($result = $mysqli->store_result()) { var_dump($result->fetch_all(MYSQLI_ASSOC)); $result->free(); } } while ($mysqli->next_result()); ]]> &example.outputs; array(1) { ["_num"]=> string(1) "0" } } array(1) { [0]=> array(1) { ["_num"]=> string(1) "1" } } ]]> Security considerations The API functions mysqli::query and mysqli::real_query do not set a connection flag necessary for activating multi queries in the server. An extra API call is used for multiple statements to reduce the damage of accidental SQL injection attacks. An attacker may try to add statements such as ; DROP DATABASE mysql or ; SELECT SLEEP(999). If the attacker succeeds in adding SQL to the statement string but mysqli::multi_query is not used, the server will not execute the injected and malicious SQL statement. query("SELECT 1; DROP TABLE mysql.user"); if (!$result) { echo "Error executing query: (" . $mysqli->errno . ") " . $mysqli->error; } ?> ]]> &example.outputs; Prepared statements Use of the multiple statement with prepared statements is not supported. See also mysqli::query mysqli::multi_query mysqli::next_result mysqli::more_results

The MySQL server supports transactions depending on the storage engine used. Since MySQL 5.5, the default storage engine is InnoDB. InnoDB has full ACID transaction support. Transactions can either be controlled using SQL or API calls. It is recommended to use API calls for enabling and disabling the autocommit mode and for committing and rolling back transactions. autocommit(false); /* Won't be monitored and recognized by the replication and the load balancing plugin */ $mysqli->query('SET AUTOCOMMIT = 0'); ]]> Optional feature packages, such as the replication and load balancing plugin, can easily monitor API calls. The replication plugin offers transaction aware load balancing, if transactions are controlled with API calls. Transaction aware load balancing is not available if SQL statements are used for setting autocommit mode, committing or rolling back a transaction. autocommit(false); $mysqli->query("INSERT INTO test(id) VALUES (1)"); $mysqli->rollback(); $mysqli->query("INSERT INTO test(id) VALUES (2)"); $mysqli->commit(); ]]> Please note, that the MySQL server cannot roll back all statements. Some statements cause an implicit commit. See also mysqli::autocommit mysqli::begin_transaction mysqli::commit mysqli::rollback

A MySQL result set contains metadata. The metadata describes the columns found in the result set. All metadata sent by MySQL is accessible through the mysqli interface. The extension performs no or negligible changes to the information it receives. Differences between MySQL server versions are not aligned. Meta data is access through the mysqli_result interface. query("SELECT 1 AS _one, 'Hello' AS _two FROM DUAL"); var_dump($result->fetch_fields()); ]]> &example.outputs; object(stdClass)#3 (13) { ["name"]=> string(4) "_one" ["orgname"]=> string(0) "" ["table"]=> string(0) "" ["orgtable"]=> string(0) "" ["def"]=> string(0) "" ["db"]=> string(0) "" ["catalog"]=> string(3) "def" ["max_length"]=> int(1) ["length"]=> int(1) ["charsetnr"]=> int(63) ["flags"]=> int(32897) ["type"]=> int(8) ["decimals"]=> int(0) } [1]=> object(stdClass)#4 (13) { ["name"]=> string(4) "_two" ["orgname"]=> string(0) "" ["table"]=> string(0) "" ["orgtable"]=> string(0) "" ["def"]=> string(0) "" ["db"]=> string(0) "" ["catalog"]=> string(3) "def" ["max_length"]=> int(5) ["length"]=> int(5) ["charsetnr"]=> int(8) ["flags"]=> int(1) ["type"]=> int(253) ["decimals"]=> int(31) } } ]]> Prepared statements Meta data of result sets created using prepared statements are accessed the same way. A suitable mysqli_result handle is returned by mysqli_stmt::result_metadata. prepare("SELECT 1 AS _one, 'Hello' AS _two FROM DUAL"); $stmt->execute(); $result = $stmt->result_metadata(); var_dump($result->fetch_fields()); ]]> See also mysqli::query mysqli_result::fetch_fields