W3C Sample Code Library libwww SQL API

# Simple SQL API

    /*
    **	(c) COPYRIGHT MIT 1995.
    **	Please first read the full copyright statement in the file COPYRIGH.
    */

This module interacts with the MYSQL C client library to perform SQL operations. It is not intended as a complete SQL API but handles most of the typical error situations talking to an SQL server so that the caller doesn't have to think about it.

This requires that you have linked against a MySQL library. See the installation instructions for details.

This module is implemented by HTSQL.c, and it is a part of the W3C Sample Code Library.

    #ifndef HTSQL_H
    #define HTSQL_H

    #include <mysql/mysql.h>

## The HTSQL Object

    typedef struct _HTSQL HTSQL;

    extern HTSQL * HTSQL_new (const char * host,
    			  const char * user, const char * pw,
    			  int flags);
    extern BOOL HTSQL_delete (HTSQL * me);

## Handling the link to the Server

### Open a connection to the SQL server

    extern BOOL HTSQL_connect (HTSQL * me);

### Close the link to the database

    extern BOOL HTSQL_close (HTSQL * me);

### You can get information about whom we are talking to by calling this function:

    extern BOOL HTSQL_version (HTSQL *		me,
    			   char **		server,
    			   unsigned int * 	protocol_version,
    			   char **		server_version,
    			   char **		client_version);

### Selecting the current database

    extern BOOL HTSQL_selectDB (HTSQL * me, const char * db);

### Getting the raw MYSQL object

After you have connected you can get the raw `MYSQL` object by calling this function

    extern MYSQL * HTSQL_getMysql (HTSQL * me);

## SQL printf

When creating queries to send to the SQL server you need to generate a lot of SQL specific strings. This function knows most of the commonly used SQL ways of handling date and time string, escaping and quoting strings and how to write integers as strings. The function works pretty much as fprintf with the following possible format arguments:

%s
  Writes a string as is. No quotation or escaping is performed. NULL is written as "`null`".
%S
  Writes a string in quotes and escapes any special SQL characters. NULL is written as "`null`".
%T
  Creates an SQL datetime stamp from a `time_t` variable looking like this `YYYY-MM-DD HH:MM:SS`. -1 is written as "`null`"
%u
  Unsigned integer
%l
  Unsigned long integer

    extern char * HTSQL_printf (char * buf, int length, char * fmt, ...);

## Issuing a Query

You can issue a query using this function. If the connection to the server was dropped then it automatically tries to reconnect

    extern BOOL HTSQL_query (HTSQL * me, const char * query);

Get information about the last inserted row's unique ID or how many rows were affected by the last query:

    extern int HTSQL_getLastInsertId (HTSQL * me);
    extern int HTSQL_GetAffectedRows (HTSQL * me);

## Handle Query Results

Call this funciton to store the SQL query result

    extern MYSQL_RES * HTSQL_storeResult (HTSQL * me);

When you are done with a query result then call this to clean up

    extern BOOL HTSQL_freeResult (MYSQL_RES * me);

    #endif