SQLite - C/C++介面 API（二）
1、開啟資料庫
SQLITE_API int sqlite3_open16(
const void *filename, /* Database filename (UTF-16) */
sqlite3 **ppDb /* OUT: SQLite db handle */
);
SQLITE_API int sqlite3_open_v2(
const char *filename, /* Database filename (UTF-8) */
sqlite3 **ppDb, /* OUT: SQLite db handle */
int flags, /* Flags */
const char *zVfs /* Name of VFS module to use */
);
/*
** CAPI3REF: Flags For File Open Operations
**
** These bit values are intended for use in the
** 3rd parameter to the [sqlite3_open_v2()] interface and
** in the 4th parameter to the [sqlite3_vfs.xOpen] method.
*/
#define SQLITE_OPEN_READONLY 0x00000001 /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_READWRITE 0x00000002 /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_CREATE 0x00000004 /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_DELETEONCLOSE 0x00000008 /* VFS only */
#define SQLITE_OPEN_EXCLUSIVE 0x00000010 /* VFS only */
#define SQLITE_OPEN_AUTOPROXY 0x00000020 /* VFS only */
#define SQLITE_OPEN_URI 0x00000040 /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_MEMORY 0x00000080 /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_MAIN_DB 0x00000100 /* VFS only */
#define SQLITE_OPEN_TEMP_DB 0x00000200 /* VFS only */
#define SQLITE_OPEN_TRANSIENT_DB 0x00000400 /* VFS only */
#define SQLITE_OPEN_MAIN_JOURNAL 0x00000800 /* VFS only */
#define SQLITE_OPEN_TEMP_JOURNAL 0x00001000 /* VFS only */
#define SQLITE_OPEN_SUBJOURNAL 0x00002000 /* VFS only */
#define SQLITE_OPEN_MASTER_JOURNAL 0x00004000 /* VFS only */
#define SQLITE_OPEN_NOMUTEX 0x00008000 /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_FULLMUTEX 0x00010000 /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_SHAREDCACHE 0x00020000 /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_PRIVATECACHE 0x00040000 /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_WAL 0x00080000 /* VFS only */
2、sqlite3_prepare函式
SQLITE_API int sqlite3_prepare(
sqlite3 *db, /* Database handle */
const char *zSql, /* SQL statement, UTF-8 encoded */
int nByte, /* Maximum length of zSql in bytes. */
sqlite3_stmt **ppStmt, /* OUT: Statement handle */
const char **pzTail /* OUT: Pointer to unused portion of zSql */
);
SQLITE_API int sqlite3_prepare_v2(
sqlite3 *db, /* Database handle */
const char *zSql, /* SQL statement, UTF-8 encoded */
int nByte, /* Maximum length of zSql in bytes. */
sqlite3_stmt **ppStmt, /* OUT: Statement handle */
const char **pzTail /* OUT: Pointer to unused portion of zSql */
);
SQLITE_API int sqlite3_prepare16(
sqlite3 *db, /* Database handle */
const void *zSql, /* SQL statement, UTF-16 encoded */
int nByte, /* Maximum length of zSql in bytes. */
sqlite3_stmt **ppStmt, /* OUT: Statement handle */
const void **pzTail /* OUT: Pointer to unused portion of zSql */
);
SQLITE_API int sqlite3_prepare16_v2(
sqlite3 *db, /* Database handle */
const void *zSql, /* SQL statement, UTF-16 encoded */
int nByte, /* Maximum length of zSql in bytes. */
sqlite3_stmt **ppStmt, /* OUT: Statement handle */
const void **pzTail /* OUT: Pointer to unused portion of zSql */
);
3、sqlite3_step
SQLITE_API int sqlite3_step(sqlite3_stmt*);
函式的返回值基於建立sqlite3_stmt引數所使用的函式，假如是使用老版本的介面sqlite3_prepare()和sqlite3_prepare16()，返回值會是 SQLITE_BUSY， SQLITE_DONE， SQLITE_ROW， SQLITE_ERROR 或 SQLITE_MISUSE，
而v2版本的介面sqlite3_prepare_v2()和sqlite3_prepare16_v2()則會同時返回這些結果碼和擴充套件結果碼。
4、sqlite3_column
這個過程從執行sqlite3_step()執行一個準備語句得到的結果集的當前行中返回一個列。每次sqlite3_step得到一個結果集的列停下後，
這個過程就可以被多次呼叫去查詢這個行的各列的值。對列操作是有多個函式，均以sqlite3_column為字首
SQLITE_API const void *sqlite3_column_blob(sqlite3_stmt*, int iCol);
BLOB資料型別是指二進位制的資料塊，比如要在資料庫中存放一張圖片，這張圖片就會以二進位制形式存放，在sqlite中對應的資料型別就是BLOB
SQLITE_API int sqlite3_column_bytes(sqlite3_stmt*, int iCol);
SQLITE_API int sqlite3_column_bytes16(sqlite3_stmt*, int iCol);
SQLITE_API double sqlite3_column_double(sqlite3_stmt*, int iCol);
SQLITE_API int sqlite3_column_int(sqlite3_stmt*, int iCol);
SQLITE_API sqlite3_int64 sqlite3_column_int64(sqlite3_stmt*, int iCol);
SQLITE_API const unsigned char *sqlite3_column_text(sqlite3_stmt*, int iCol);
SQLITE_API const void *sqlite3_column_text16(sqlite3_stmt*, int iCol);
SQLITE_API int sqlite3_column_type(sqlite3_stmt*, int iCol);
SQLITE_API sqlite3_value *sqlite3_column_value(sqlite3_stmt*, int iCol);
5． sqlite3_finalize
int sqlite3_finalize(sqlite3_stmt *pStmt);
這個過程銷燬前面被sqlite3_prepare建立的準備語句，每個準備語句都必須使用這個函式去銷燬以防止記憶體洩露。
程式設計例項：
1 #include <stdio.h> 2 #include <string.h> 3 #include "../Sqlite3/sqlite3.h" 4 5 int main (int argc, char *argv[]) 6 { 7 char *p_query = "SELECT * FROM PERSON;"; 8 char *p_name = "mytest.db"; 9 sqlite3_stmt *p_stmt = NULL; 10 char *p_err_msg = NULL; 11 int rec = 0; 12 sqlite3 *p_db = NULL; 13 14 if (SQLITE_OK != (rec = sqlite3_open_v2(p_name, &p_db, SQLITE_OPEN_READONLY, NULL) )) 15 { 16 printf("sqlite3_open_v2 function err %s\n"); 17 return -1; 18 } 19 20 if (SQLITE_OK != (rec = sqlite3_prepare_v2(p_db, p_query, -1, &p_stmt, NULL))) 21 { 22 printf("sqlite3_prepare_v2 function err : %s\n", sqlite3_errmsg(p_db)); 23 sqlite3_close(p_db); 24 return -1; 25 } 26 27 while (SQLITE_ROW == sqlite3_step(p_stmt)) 28 { 29 printf("ID = %d\n", sqlite3_column_int64(p_stmt, 0)); 30 printf("NAME = %s\n", sqlite3_column_text(p_stmt,1)); 31 printf("AGE = %d\n", sqlite3_column_int(p_stmt, 2)); 32 printf("\n"); 33 } 34 35 sqlite3_close(p_db); 36 p_db = NULL; 37 38 return 0; 39 }
執行結果：
