iOS SQLite

一、基本的数据库操作
1-1、加libsqlite3.0.dylib库， #import  "/usr/include/sqlite3.h" 
1-2、打开数据库
int sqlite3_open(
const char *filename, /* Database filename (UTF-8) */
sqlite3 **ppDb /* OUT: SQLite db handle */
);

2、对表的操作

int sqlite3_exec( 
sqlite3*, /* An open database */
const char *sql, /* SQL to be evaluated */
int (*callback)(void*,int,char**,char**), /*Callbk func*/
void *, /* 1st argument to callback*/
char **errmsg /* Error msg written here */
);
 
SQLite有五种数据存储类型：
•  INTEGER. 整型值
•  REAL. 浮点类型（An  8-byte IEEE floating-point storage representing a floating-point number. ）
•  TEXT. 字符串 （A storage area for text. The text can be in any of the following encodings: UTF-8, UTF-16BE, or  UTF-16-LE. ）
•  BLOB. 大数据 （Used to store data exactly as entered — for example, an image. ）
•  NULL. 空值 （Used to store  the value  NULL.）

3、示例

#import "/usr/include/sqlite3.h" 
int main(int argc, char *argv[]) { 
char *sqlStatement; 
sqlite3 *pDb; 
char *errorMsg; 
int returnCode; 
char *databaseName; 
databaseName = "financial.db"; 
returnCode = sqlite3_open(databaseName, &pDb); 
if(returnCode!=SQLITE_OK) { 
　　fprintf(stderr, "Error in opening the database. Error: %s", 
　　sqlite3_errmsg(pDb)); 
　　sqlite3_close(pDb); 
　　return -1; 
} 
sqlStatement = "DROP TABLE IF EXISTS stocks"; 
returnCode = sqlite3_exec(pDb, sqlStatement, NULL, NULL, &errorMsg); 
if(returnCode!=SQLITE_OK) { 
　　fprintf(stderr, 
　　"Error in dropping table stocks. Error: %s", errorMsg); 
　　sqlite3_free(errorMsg); 
} 
sqlStatement = "CREATE TABLE stocks (symbol VARCHAR(5), " 
"purchasePrice FLOAT(10,4), " 
"unitsPurchased INTEGER, " 
"purchase_date VARCHAR(10))"; 
returnCode = sqlite3_exec(pDb, sqlStatement, NULL, NULL, &errorMsg); 
if(returnCode!=SQLITE_OK) { 
fprintf(stderr, "Error in creating the stocks table. Error: %s", 
errorMsg); 
sqlite3_free(errorMsg); 
} 
insertStockPurchase(pDb, "ALU", 14.23, 100, "03-17-2012"); 
insertStockPurchase(pDb, "GOOG", 600.77, 20, "01-09-2012"); 
insertStockPurchase(pDb, "NT", 20.23,140, "02-05-2012"); 
insertStockPurchase(pDb, "MSFT", 30.23, 5, "01-03-2012"); 
sqlite3_close(pDb); 
return 0; 
} 

void insertStockPurchase(sqlite3 *pDb, const char*symbol, 
float price, int units, const char* theDate){ 
char *errorMsg; 
int returnCode; 
char *st; 
st = sqlite3_mprintf("INSERT INTO stocks VALUES" 
" (’%q’, %f, %d, ’%q’)", symbol, price, units, theDate); 
returnCode = sqlite3_exec(pDb, st, NULL, NULL, &errorMsg); 
if(returnCode!=SQLITE_OK) { 
fprintf(stderr, 
"Error in inserting into the stocks table. Error: %s", 
errorMsg); 
sqlite3_free(errorMsg); 
} 
sqlite3_free(st); 
}
 
二、Processing Row Results
利用回调函数来处理每行的数据
 
三、预申明 （Prepared Statements）
对于不返回数据的sql操作（insert,drop,create），用sqlite3_exec()；对于返回数据的操作(select)，
3-1、三个阶段：
准备（Preparation），执行（Execution），结束（Finalization）
准备 - sqlite3_prepare_v2(sqlite3  *db,const  char  *zSql ,int  nBytes,sqlite3_stmt  **ppStmt,const  char  **pzTail)
执行 - sqlite3_step(sqlite3_stmt*);
结束 - sqlite3_finalize(sqlite3_stmt  *pStmt);
示例：
#import "/usr/include/sqlite3.h" 
int main(int argc, char *argv[]) { 
　　char *sqlStatement; 
　　sqlite3 *database; 
　　int returnCode; 
　　char *databaseName; 
　　sqlite3_stmt *statement; 
　　databaseName = "financial.db"; 
　　returnCode = sqlite3_open(databaseName, &database); 
　　if(returnCode!=SQLITE_OK) { 
　　　　fprintf(stderr, "Error in opening the database. Error: %s", 
　　　　sqlite3_errmsg(database)); 
　　　　sqlite3_close(database); 
　　　　return -1; 
　　} 

sqlStatement = sqlite3_mprintf( 

　　"SELECT S.symbol, S.unitsPurchased, " 
　　"S.purchasePrice FROM stocks AS S WHERE " 
　　"S.purchasePrice >= %f", 30.0); 
　　returnCode = 
　　sqlite3_prepare_v2(database, sqlStatement, strlen(sqlStatement), &statement, NULL); 
　　if(returnCode != SQLITE_OK) { 
　　fprintf(stderr, "Error in preparation of query. Error: %s", 
　　sqlite3_errmsg(database)); 
　　sqlite3_close(database); 
　　return -1; 
　　} 
　　returnCode = sqlite3_step(statement); 
　　while(returnCode == SQLITE_ROW){ 
　　char *symbol; 
　　int units; 
　　double price; 
　　symbol = sqlite3_column_text(statement, 0); 
　　units = sqlite3_column_int(statement, 1); 
　　price = sqlite3_column_double(statement, 2); 
　　printf("We bought %d from %s at a price equal to %.4f\n", 
　　units, symbol, price); 
　　returnCode = sqlite3_step(statement); 
　　} 
　　sqlite3_finalize(statement); 
　　sqlite3_free(sqlStatement); 
　　return 0; 
}
 
四、用户自定义函数 (User-Defined Functions)
sqlite3_create_function()
 
五、存储二进制大对象(Storing BLOBs)
 
六、检索二进制大对象（Retrieving BLOBs）