SQLite 用户自定义函数举例

SQLite 用户自定义函数举例

作者：tamsyn  来源：[email protected]  时间：2007-3-20  【 字体：大 中 小 】 〖 双击滚屏 〗

#include <stdio.h> #include <string.h> #include <stdlib.h> #include <time.h> #include <malloc.h> #include <assert.h> #include <sqlite3.h> #define SELECT_QUERY    "SELECT host_id, geturl(desc) FROM host_table; void host2url_func( sqlite3_context * ctx, int argc, sqlite3_value ** argv ) {  if ( argc != 1 ) return;  char * httpurl = NULL;  switch( sqlite3_value_type( argv[ 0 ] ) )  {   case SQLITE_NULL:   {    sqlite3_result_text( ctx, "NULL", 4, SQLITE_STATIC );    break;   }   case SQLITE_TEXT:   {    httpurl = ( char * ) malloc( strlen( sqlite3_value_text( argv[0] ) ) + 8 );    if ( httpurl == 0 ) return;    sprintf( httpurl, "http://%s", sqlite3_value_text( argv[ 0 ] ) );    sqlite3_result_text( ctx, httpurl, strlen( httpurl ), SQLITE_TRANSIENT );    free( httpurl );    httpurl = NULL;    break;   }   default:    sqlite3_result_text( ctx, "about:blank", 11, SQLITE_STATIC );  } } static int callback(void *NotUsed, int argc, char **argv, char **azColName) {    int i;    for(i=0; i<argc; i++){       printf("%s = %s/n", azColName[i], argv[i] ? argv[i] : "NULL");    }    printf("/n");    return 0; } int main( int argc, char **argv ) {    sqlite3 *db;    char *zErrMsg = 0;    int rc;    if( argc!=3 )    {   fprintf(stderr, "Usage: %s DATABASE SQL-STATEMENT/n", argv[0]);   exit(1);    }    rc = sqlite3_open(argv[1], &db);    if( rc ){   fprintf(stderr, "Can't open database: %s/n", sqlite3_errmsg(db));   sqlite3_close(db);   exit(1);    }       sqlite3_create_function( db, "geturl", 1, SQLITE_ANY, NULL, host2url_func, NULL, NULL );    rc = sqlite3_exec(db, argv[2], callback, 0, &zErrMsg);    if( rc!=SQLITE_OK ){   fprintf(stderr, "SQL error: %s/n", zErrMsg);    }    sqlite3_close(db);    return 0; }