Chapter 6 C API Prepared Statement Interface

Table of Contents

6.1 Overview of the C API Prepared Statement Interface

6.2 C API Prepared Statement Data Structures

6.2.1 C API Prepared Statement Type Codes

6.2.2 C API Prepared Statement Type Conversions

6.3 C API Prepared Statement Function Reference

6.4 C API Prepared Statement Function Descriptions

6.4.1 mysql_stmt_affected_rows()

6.4.2 mysql_stmt_attr_get()

6.4.3 mysql_stmt_attr_set()

6.4.4 mysql_stmt_bind_param()

6.4.5 mysql_stmt_bind_result()

6.4.6 mysql_stmt_close()

6.4.7 mysql_stmt_data_seek()

6.4.8 mysql_stmt_errno()

6.4.9 mysql_stmt_error()

6.4.10 mysql_stmt_execute()

6.4.11 mysql_stmt_fetch()

6.4.12 mysql_stmt_fetch_column()

6.4.13 mysql_stmt_field_count()

6.4.14 mysql_stmt_free_result()

6.4.15 mysql_stmt_init()

6.4.16 mysql_stmt_insert_id()

6.4.17 mysql_stmt_next_result()

6.4.18 mysql_stmt_num_rows()

6.4.19 mysql_stmt_param_count()

6.4.20 mysql_stmt_param_metadata()

6.4.21 mysql_stmt_prepare()

6.4.22 mysql_stmt_reset()

6.4.23 mysql_stmt_result_metadata()

6.4.24 mysql_stmt_row_seek()

6.4.25 mysql_stmt_row_tell()

6.4.26 mysql_stmt_send_long_data()

6.4.27 mysql_stmt_sqlstate()

6.4.28 mysql_stmt_store_result()

The MySQL client/server protocol provides for the use of prepared statements. This capability uses the MYSQL_STMT statement handler data structure returned by the mysql_stmt_init() initialization function. Prepared execution is an efficient way to execute a statement more than once. The statement is first parsed to prepare it for execution. Then it is executed one or more times at a later time, using the statement handler returned by the initialization function.

Prepared execution is faster than direct execution for statements executed more than once, primarily because the query is parsed only once. In the case of direct execution, the query is parsed every time it is executed. Prepared execution also can provide a reduction of network traffic because for each execution of the prepared statement, it is necessary only to send the data for the parameters.

Prepared statements might not provide a performance increase in some situations. For best results, test your application both with prepared and nonprepared statements and choose whichever yields best performance.

Another advantage of prepared statements is that it uses a binary protocol that makes data transfer between client and server more efficient.

For a list of SQL statements that can be used as prepared statements, see Prepared Statements.

Metadata changes to tables or views referred to by prepared statements are detected and cause automatic repreparation of the statement when it is next executed. For more information, see Caching of Prepared Statements and Stored Programs.