iPhone中的SQLite应用
From :http://linglong117.blog.163.com/blog/static/277145472009111403520676/SQLite是基于C的API，在iPhone中的运行速度超级快（在苹果网站上也有一个对比，确实应该是速度最快的）。
由于在iPhone3.0上已经支持了Core Data，是苹果一个新的API，并且是基于SQlite的。速度也是非常快吧，信不信由你。所以我们对SQLite仅需要懂一些即可，以下是一些基础信息
//============
首先在FrameWorks 中加入SQLite 的库: lib/libsqlite3.dylib
完整路径如下：
/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS3.0.sdk/usr/lib/libsqlite3.dylib
然后包含头文件#import <sqlite3.h>
一般操作：
//=============
//databasePath 数据库路径
//database 数据库名
int n = sqlite3_open(, &database); //打开数据库
if(n != SQLITE_OK){ //判断数据库是否打开
NSLog(@"can not open the database");
return;
}
//执行sql 语句
sqlite3_stmt *stmt;
char *sql = "SELECT TimeDesc FROM tblTime WHERE isActivated=1"; //sql 语句
sqlite3_prepare_v2(database, sql, -1, &stmt, NULL);
int code = sqlite3_step(stmt);
NSMutableArray *arrayData = [ init];
NSMutableDictionary *dicTimeDesc = [ init];
//把sql 语句的查询结果存储到 NSMutableArray 中
while (code == SQLITE_ROW) {
char *c;
NSString *s;
c = (char *)sqlite3_column_text(stmt, 0);
s = ;
;
;
//int n;
//n = sqlite3_column_int(stmt2,0);
;
code = sqlite3_step(stmt);
}
sqlite3_finalize(stmt);
sqlite3_close(database); //关闭数据库
//带参数的sql 语句
sqlite3_stmt *stmt;
char *sql = "SELECT SNo,BrandName,PicFileName,FolderGUID,PicDesc,PicDescLocation,IconSpecName,StyleName,PicFileName_H FROM tblProduct where BrandName = ? order by SNo";
sqlite3_prepare_v2(database, sql, -1, &stmt, NULL);
sqlite3_bind_text(stmt, 1, , -1, SQLITE_TRANSIENT);
//
NSMutableDictionary *d;
char *c;
NSString *s;
//
int code = sqlite3_step(stmt);
while (code == SQLITE_ROW) {
//sql 语句检索结果
}
//=========
//执行事务
@try {
sqlite3_exec(database,"BEGIN TRANSACTION",0,0,0); //事务开始
NSString *s = [ initWithUTF8String:[要执行的sql 语句 UTF8String]];
char *sql = (char *) ;
int r = sqlite3_exec( database, sql , 0, 0, 0 );
if(r != SQLITE_OK){
//NSLog(@" sql: %@" ,s);
//NSLog(@"r = %d",r);
}
NSLog(@"updateSql %@",ssql);
NSLog(@"r = %d",r);
;
}
@catch (NSException * em) {
NSLog(@"failed to read %@",);
}
@finally {
//NSLog(@"failed to read %@",);
}
}
int result = sqlite3_exec(database,"COMMIT",0,0,&error); //COMMIT
//==============
//以下内容为网络上摘取的，我没经过验证，可以做为参考
【1】打开数据库，如果没有，那么创建一个
sqlite3* database_;
-(BOOL) open{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = ;
NSString *path = ;
NSFileManager *fileManager = ;
BOOL find = ;
//找到数据库文件mydb.sql
if (find) {
NSLog(@"Database file have already existed.");
if(sqlite3_open(, &database_) != SQLITE_OK) {
sqlite3_close(database_);
NSLog(@"Error: open database file.");
return NO;
}
return YES;
}
if(sqlite3_open(, &database_) == SQLITE_OK) {
bFirstCreate_ = YES;
createChannelsTable:database_];//在后面实现函数createChannelsTable
return YES;
} else {
sqlite3_close(database_);
NSLog(@"Error: open database file.");
return NO;
}
return NO;
}
【2】创建表格
//创建表格，假设有五个字段，（id，cid，title，imageData ，imageLen ）
//说明一下，id为表格的主键，必须有。
//cid，和title都是字符串，imageData是二进制数据，imageLen 是该二进制数据的长度。
- (BOOL) createChannelsTable:(sqlite3*)db{
char *sql = "CREATE TABLE channels (id integer primary key, \
cid text, \
title text, \
imageData BLOB, \
imageLen integer)";
sqlite3_stmt *statement;
if(sqlite3_prepare_v2(db, sql, -1, &statement, nil) != SQLITE_OK) {
NSLog(@"Error: failed to prepare statement:create channels table");
return NO;
}
int success = sqlite3_step(statement);
sqlite3_finalize(statement);
if ( success != SQLITE_DONE) {
NSLog(@"Error: failed to dehydrate:CREATE TABLE channels");
return NO;
}
NSLog(@"Create table 'channels' successed.");
return YES;
}
【3】向表格中插入一条记录
假设channle是一个数据结构体，保存了一条记录的内容。
- (BOOL) insertOneChannel:(Channel*)channel{
NSData* ImageData = UIImagePNGRepresentation( channel.image_);
NSInteger Imagelen = ;
sqlite3_stmt *statement;
static char *sql = "INSERT INTO channels (cid,title,imageData,imageLen)\
VALUES(?,?,?,?)";
//问号的个数要和(cid,title,imageData,imageLen)里面字段的个数匹配，代表未知的值，将在下面将值和字段关联。
int success = sqlite3_prepare_v2(database_, sql, -1, &statement, NULL);
if (success != SQLITE_OK) {
NSLog(@"Error: failed to insert:channels");
return NO;
}
//这里的数字1，2，3，4代表第几个问号
sqlite3_bind_text(statement, 1, , -1, SQLITE_TRANSIENT);
sqlite3_bind_text(statement, 2, , -1, SQLITE_TRANSIENT);
sqlite3_bind_blob(statement, 3, , Imagelen, SQLITE_TRANSIENT);
sqlite3_bind_int(statement, 4, Imagelen);
success = sqlite3_step(statement);
sqlite3_finalize(statement);
if (success == SQLITE_ERROR) {
NSLog(@"Error: failed to insert into the database with message.");
return NO;
}
NSLog(@"Insert One Channel#############:id = %@",channel.id_);
return YES;
}
【4】数据库查询
这里获取表格中所有的记录，放到数组fChannels中。
- (void) getChannels:(NSMutableArray*)fChannels{
sqlite3_stmt *statement = nil;
char *sql = "SELECT * FROM channels";
if (sqlite3_prepare_v2(database_, sql, -1, &statement, NULL) != SQLITE_OK) {
NSLog(@"Error: failed to prepare statement with message:get channels.");
}
//查询结果集中一条一条的遍历所有的记录，这里的数字对应的是列值。
while (sqlite3_step(statement) == SQLITE_ROW) {
char* cid = (char*)sqlite3_column_text(statement, 1);
char* title = (char*)sqlite3_column_text(statement, 2);
Byte* imageData = (Byte*)sqlite3_column_blob(statement, 3);
int imageLen = sqlite3_column_int(statement, 4);
Channel* channel = [ init];
if(cid)
channel.id_ = ;
if(title)
channel.title_ = ;
if(imageData){
UIImage* image = ];
channel.image_ = image;
}
;
;
}
sqlite3_finalize(statement);
}
//===================
打开数据库
sqlite3 *database = NULL; //建立一个sqlite数据库变量 int sqlite3_open(const char *文件名, sqlite3 **db); //那个文件名需要是cString， //之后那个db对象使用我们建立的database变量 //以下是一个开打的例子：NSString *fileAddress = [[NSBundle mainBundle] pathForResource:@"预存文件的文件名" ofType:@"db"]; //db是扩展名 if(sqlite3_open([fileAddress UTF8String], &database) == SQLITE_OK) //UTF8String方法转换NSString为cString
执行一个SQLite语句：
int sqlite3_exec(sqlite3 *db, const char *sql, int (*callback)(void*,int,char**,char**), void *context, char **error);
关闭一个数据库：
int sqlite3_close(sqlite3 *db); //这个不用解释了吧
一个响应函数的格式：
int callback(void *context, int count, char **values, char **columns);
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