IOS中的sqlite数据库的使用
[置顶] IOS中的sqlite数据库的使用
分类： 数据库技术 IOS开发
2012-03-11 14:29
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http://blog.csdn.net/cubepeng/article/details/7336091
sqlite在移动客户端的开发非常常见，我之前做过一个ios项目中也用到，无耐技术水平有限，做的不是很好！但是一查网上这方面的总结不是很多，可能大牛们都忙着赚钱去了，我就献丑将我在项目中用到的东西贡献出来，有什么不好的地方请指教。值得说明的是我是看了某个网站贴出的demo而稍作改进，若此君不小心看到本篇小作，请指出，如有需要可以删除此文。下面开始介绍我的做的东西：
1.用到主要的函数有sqlite3_open,sqlite3_close,sqlite3_exe这里我不解释这些函数的用法了（http://www.cppblog.com/woaidongmao/archive/2009/06/23/88361.html，有详细介绍），直接进入正题。
2.这个例子里面涉及如下几个文件，DatabaseConnection,DatabaseStatement,DataBaseCenter.在这个demo中我只要用到一个数据库
DatabaseConnection.h
- #import <Foundation/Foundation.h>
- #import "sqlite3.h"
- #import "DataStatement.h"
- @interface DataConnection : NSObject
- //建表
- +(void)exeCreate:(NSString*)createString;
- +(sqlite3*)sharedDataBase; //访问单例
- +(void)closeDataBase; //关闭数据库连接，置空句柄
- +(void)beginTransaction; //开始事务
- +(void)commitTransaction; //提交事务
- + (DataStatement*)statementWithQuery:(const char*)sql; //初始化一个连接
- +(void)alert; //提出警告
- +(int)getRowsWithQury:(const char*)sql; //获取select语句中结果数据的行数
- @end
DatabaseConnection.m
- #import "DataConnection.h"
- #define DATABASENAME @"Demo.db"
- static sqlite3 *dataBaseInstance = nil;
- @implementation DataConnection
- +(void)exeCreate:(NSString*)createString
- {
- char *errorMsg;
- if (sqlite3_exec(dataBaseInstance, [createString UTF8String], NULL, NULL, &errorMsg)!=SQLITE_OK)
- {
- NSAssert1(0, @"can not create users table,'%s'.",errorMsg);
- }
- [self closeDataBase];
- }
- +(sqlite3*)openDataBase:(NSString*)dataBaseName
- {
- NSArray *array = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
- NSString * path = [array objectAtIndex:0];
- NSString * databasePath = [path stringByAppendingPathComponent:dataBaseName];
- if (sqlite3_open([databasePath UTF8String], &dataBaseInstance)!=SQLITE_OK)
- {
- NSLog(@"can not open the database:%@",sqlite3_errmsg(dataBaseInstance));
- sqlite3_close(dataBaseInstance);
- return nil;
- }
- return dataBaseInstance;
- }
- +(sqlite3*)sharedDataBase
- {
- if (nil == dataBaseInstance) {
- @synchronized(self)
- {
- dataBaseInstance = [self openDataBase:DATABASENAME];
- }
- if (nil == dataBaseInstance) {
- [self createEditableCopyofDataBaseIfNeeded:YES];
- }
- }
- return dataBaseInstance;
- }
- +(void)commitTransaction
- {
- char *errMessage;
- sqlite3_exec(dataBaseInstance, "COMMIT", nil, nil, &errMessage);
- }
- +(void)beginTransaction
- {
- char *errMessage;
- sqlite3_exec(dataBaseInstance, "BEGIN", nil, nil, &errMessage);
- }
- +(DataStatement*)statementWithQuery:(const char*)sql
- {
- [self sharedDataBase];
- DataStatement *dataStatement = [DataStatement statementWithDB:dataBaseInstance withQuery:sql];
- return dataStatement;
- }
- +(void)closeDataBase
- {
- sqlite3_close(dataBaseInstance);
- dataBaseInstance = nil; //数据库句柄一定要置空，不然重新建立连接的时候会有问题
- }
- +(void)alert
- {
- NSString *errorString = [NSString stringWithUTF8String: sqlite3_errmsg(dataBaseInstance)];
- CLog(@"alert message:%@",errorString);
- }
Datastatement.h
- #import <Foundation/Foundation.h>
- #import "sqlite3.h"
- @interface DataStatement : NSObject
- {
- sqlite3_stmt* stmt;
- }
- +(id)statementWithDB:(sqlite3*)DB withQuery:(const char *)sql;
- -(id)initWithDB:(sqlite3*)db withQuery:(const char *)sql;
- // method
- - (int)step;
- - (void)reset;
- - (int)getResultCount;
- // Getter
- - (NSString*)getString:(int)index;
- - (int)getInt32:(int)index;
- - (long long)getInt64:(int)index;
- - (NSData*)getData:(int)index;
- - (double)getDouble:(int)index;
- // Binder
- - (void)bindString:(NSString*)value forIndex:(int)index;
- - (void)bindInt32:(int)value forIndex:(int)index;
- - (void)bindInt64:(long long)value forIndex:(int)index;
- - (void)bindData:(NSData*)data forIndex:(int)index;
- - (void)bindDouble:(double)value forIndex:(int)index;
- @end
Datastatement.m
- //
- // DataStatement.m
- // mainPage
- //
- // Created by myiee on 11-11-3.
- // Copyright (c) 2011年 __MyCompanyName__. All rights reserved.
- //
- #import "DataStatement.h"
- @implementation DataStatement
- -(void)dealloc
- {
- [super dealloc];
- sqlite3_finalize(stmt);
- }
- -(id)initWithDB:(sqlite3 *)db withQuery:(const char *)sql
- {
- self = [super init];
- if (sqlite3_prepare_v2(db, sql, -1, &stmt, NULL)!=SQLITE_OK) {
- NSAssert2(0, @"can not compare '%s',(%s)", sql, sqlite3_errmsg(db));
- }
- return self;
- }
- +(id)statementWithDB:(sqlite3 *)DB withQuery:(const char *)sql
- {
- return [[[DataStatement alloc]initWithDB:DB withQuery:sql]autorelease];
- }
- -(int)step
- {
- return sqlite3_step(stmt);
- }
- -(void)reset
- {
- sqlite3_reset(stmt);
- }
- - (int)getResultCount
- {
- return sqlite3_column_count(stmt);
- }
- -(NSString*)getString:(int)index
- {
- if (NULL != (char*)sqlite3_column_text(stmt, index)) {
- return [NSString stringWithUTF8String:(char*)sqlite3_column_text(stmt, index)];
- }
- else
- return nil;
- }
- -(int)getInt32:(int)index
- {
- return sqlite3_column_int(stmt, index);
- }
- -(long long)getInt64:(int)index
- {
- return sqlite3_column_int64(stmt, index);
- }
- -(NSData*)getData:(int)index
- {
- int length = sqlite3_column_bytes(stmt, index);
- return [NSData dataWithBytes:sqlite3_column_blob(stmt, index) length:length];
- }
- -(double)getDouble:(int)index
- {
- return sqlite3_column_double(stmt, index);
- }
- -(void)bindData:(NSData *)data forIndex:(int)index
- {
- sqlite3_bind_blob(stmt, index, data.bytes, data.length, SQLITE_TRANSIENT);
- }
- -(void)bindString:(NSString *)value forIndex:(int)index
- {
- sqlite3_bind_text(stmt, index,[value UTF8String] , -1, SQLITE_TRANSIENT);
- }
- -(void)bindInt32:(int)value forIndex:(int)index
- {
- sqlite3_bind_int(stmt, index,value);
- }
- -(void)bindInt64:(long long)value forIndex:(int)index
- {
- sqlite3_bind_int64(stmt, index, value);
- }
- -(void)bindDouble:(double)value forIndex:(int)index
- {
- sqlite3_bind_double(stmt, index, value);
- }
- @end
- #import <Foundation/Foundation.h>
- #import "sqlite3.h"
- //#import "Users.h"
- #import "DataConnection.h"
- #import "DataStatement.h"
- @interface DataBaseCenter : NSObject
- {
- sqlite3_stmt *stmt;
- }
- + (void)createDatabase;
- //user
- + (id)getLastLoginUser;
- + (BOOL)updateUser:(NSDictionary*)dictionary;
- + (id)getUserWithName:(NSString*)name;
- @end
DatabaseCenter.m
- +(void)createDatabase
- {
- [DataConnection sharedDataBase];
- NSString *createUser = @"create table if not exists user(userId integer primary key,name text not null,password text not null,flag integer not null);";
- //这个数据库中只建立了一个user的数据表，当flag为1的时候代表这条用户的数据纪录是最后一个合法登陆的数据用户
- [DataConnection exeCreate:createDataString];
- }
- + (id)getLastLoginUser
- {
- static DataStatement *stmt = nil;
- if (!stmt)
- {
- stmt = [DataConnection statementWithQuery:"select * from user where flag = 1"];
- [stmt retain];
- }
- if (SQLITE_ROW != [stmt step]) {
- [stmt reset];
- return nil;
- }
- NSString *userName = [stmt getString:1];
- NSString *password = [stmt getString:2];
- NSDictionary *dic = [[NSDictionary alloc]initWithObjectsAndKeys:userName,@"name",password,@"password", nil];
- return [dic autorelease];
- }
- + (BOOL)updateUser:(NSDictionary*)dictionary //将当前的的数据的flag更新为1 ，其他置为0,当前的用户数据不存在的时候插入到表中
- {
- NSDictionary *dic = [dictionary retain];
- NSString *userName = [dic objectForKey:@"name"];
- NSString *password = [dic objectForKey:@"password"];
- int flag = [[dic objectForKey:@"flag"]intValue];
- NSString *selectString = [NSString stringWithFormat:@"select * from user where name = '%@'",userName];
- const char *cString = [selectString cStringUsingEncoding:NSUTF8StringEncoding ];
- unsigned int r = [DataConnection getRowsWithQury:cString];
- DataStatement *stmt = nil;
- if (!stmt) {
- stmt = [DataConnection statementWithQuery:"update user set flag = 0 where flag != 0"];
- [stmt retain];
- }
- if (SQLITE_DONE != [stmt step]) {
- [stmt release];
- [stmt reset];
- stmt = nil;
- return NO;
- }
- [stmt release];
- stmt = nil;
- if (r ==1 ) {//当之前已经存在该数据的时候更新变为1
- NSString *stmtString = [NSString stringWithFormat:@"update user set flag = 1 where name = '%@'",userName];
- stmt = [DataConnection statementWithQuery:[stmtString UTF8String]];
- [stmt retain];
- if (SQLITE_DONE != [stmt step]) {
- [stmt release];
- [stmt reset];
- stmt = nil;
- return NO;
- }
- [stmt release];
- }
- else
- {
- stmt = nil;
- if (!stmt) {
- stmt = [DataConnection statementWithQuery:"insert or replace into user(name,password,flag) values(?,?,?)"];
- [stmt retain];
- }
- [stmt bindString:userName forIndex:1];
- [stmt bindString:password forIndex:2];
- [stmt bindInt32:flag forIndex:3];
- if (SQLITE_DONE != [stmt step]) {
- [stmt reset];
- [stmt release];
- return NO;
- }
- [stmt release];
- }
- return YES;
- }
- //根据用户名获取用户的数据
- + (id)getUserWithName:(NSString *)name
- {
- DataStatement *stmt = nil;
- NSString *selectString = [NSString stringWithFormat:@"select * from user where name = %@",name];
- const char *cString = [selectString cStringUsingEncoding:NSUTF8StringEncoding];
- if (!stmt)
- {
- stmt = [DataConnection statementWithQuery:cString];
- [stmt retain];
- }
- if (SQLITE_ROW != [stmt step]) {
- [stmt reset];
- return nil;
- }
- NSString *userName = [stmt getString:1];
- NSString *password = [stmt getString:2];
- NSDictionary *dic = [[NSDictionary alloc]initWithObjectsAndKeys:userName,@"name",password,@"password", nil];
- return [dic autorelease];
- }
现在我们能在任何一个地方使用这个单例了，现在我们新建一个文件TestDatabase文件中的使用他
- - (void)loadView
- {
- [super loadView];
- [DataBasecenter createDatabase];
- NSDictionary *dic = [NSDictionary dicionaryValueAndkeys:@"name",@"name",@"1234567",@"password",@"1",@"flag"];
- [DataBaseCenter updateUser:dic];
- }
这样我们就能使用数据库了，其实挺简单的。
4.我在这个例子中只有一个数据库，所以用单例很方便，当然你想建立多个数据库，那也是很简单，一个数据库对应的一个数据库connection，一个connection可以对应多个statement，我这样的封装适合单个数据库，你也可以封装成工厂的方式，见前面我对xml解析的一文，也是很简单的。
总结：对sqlite的使用，我之前看到一个很好的例子，我将转过来作为一个单独的系列。
注：转载请注明出处。