iPhone开发之SQLite的使用

SQLite确实是个好东西，不需要引擎，啥程序都可以使用，特别在嵌入式开发中使用得特别多。

记得刚开始在iPhone中使用SQLite的时候，琢磨了几天，才完成增删改查，费了九牛二虎之力呀。

iPhone中使用SQLite其实也不算简单，链接数据库、执行SQL，都感觉挺复杂的。经过多番研究，将iPhone中SQLite的使用方法封装到一个类中了，增删改查使用起来都极其方便，已经在多个项目中使用了我封装的这个类，目前还没发现有啥bug。

SQLiteOperation.h

#import <Foundation/Foundation.h>
#import <sqlite3.h>
#import <CoreLocation/CoreLocation.h>

@interface SQLiteOperation : NSObject {
 sqlite3 *database;
 NSString *path;
}

- (void)readyDatabse;
- (void)getPath;
- (NSMutableArray *)selectData:(NSString *)sql resultColumns:(int)col;
- (BOOL)dealData:(NSString *)sql paramArray:(NSArray *)param;

@end

SQLiteOperation.m

#import "SQLiteOperation.h"

@implementation SQLiteOperation

#pragma mark 准备数据库
- (void)readyDatabse {
 BOOL success;
 NSFileManager *fileManager = [NSFileManager defaultManager];
 NSError *error;
 NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
 NSString *documentsDirectory = [paths objectAtIndex:0];
 NSString *writableDBPath = [documentsDirectory stringByAppendingPathComponent:@"test.sqlite"];
 success = [fileManager fileExistsAtPath:writableDBPath];
 [self getPath];
 if (success) return;
 // The writable database does not exist, so copy the default to the appropriate location.
 NSString *defaultDBPath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"test.sqlite"];
 success = [fileManager copyItemAtPath:defaultDBPath toPath:writableDBPath error:&error];
 if (!success) {
 NSAssert1(0, @"Failed to create writable database file with message '%@'.", [error localizedDescription]);
 }
}

#pragma mark 路径
- (void)getPath{
 NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
 NSString *documentsDirectory = [paths objectAtIndex:0];
 path = [documentsDirectory stringByAppendingPathComponent:@"test.sqlite"];
}

#pragma mark 查询数据库
/************
sql：sql语句
col：sql语句需要操作的表的所有字段数
***********/
- (NSMutableArray *)selectData:(NSString *)sql resultColumns:(int)col {
 [self readyDatabse];
 NSMutableArray *returnArray = [[[NSMutableArray alloc] init] autorelease];//所有记录
 if (sqlite3_open([path UTF8String], &database) == SQLITE_OK) {
 sqlite3_stmt *statement = nil;
 if (sqlite3_prepare_v2(database, [sql UTF8String], -1, &statement, NULL) == SQLITE_OK) {
 while (sqlite3_step(statement) == SQLITE_ROW) {
    NSMutableArray *row = [[NSMutableArray alloc] init];//一条记录
    //NSLog(@"=====%@",statement);
    for(int i=0; i<col; i++){
     [row addObject:[NSString stringWithFormat:@"%s", sqlite3_column_text(statement, i)]];
    }
    [returnArray addObject:row];
    [row release];
 }//end while
 }else {
   NSLog(@"Error: failed to prepare");
   return NO;
  }//end if
  //NSLog(@"returnArray：%@",returnArray);
  return returnArray;
 sqlite3_finalize(statement);
 } else {
 sqlite3_close(database);
 NSAssert1(0, @"Failed to open database with message '%s'.", sqlite3_errmsg(database));
 }//end if
 sqlite3_close(database);
 return returnArray;
}

#pragma mark 增，删，改数据库
/************
sql：sql语句
param：sql语句中?对应的值组成的数组
***********/
- (BOOL)dealData:(NSString *)sql paramArray:(NSArray *)param {
 [self readyDatabse];
 if (sqlite3_open([path UTF8String], &database) == SQLITE_OK) {
 sqlite3_stmt *statement = nil;
 int success = sqlite3_prepare_v2(database, [sql UTF8String], -1, &statement, NULL);
  if (success != SQLITE_OK) {
   NSLog(@"Error: failed to prepare");
   return NO;
  }
  //绑定参数
  NSInteger max = [param count];
  for (int i=0; i<max; i++) {
   NSString *temp = [param objectAtIndex:i];
   sqlite3_bind_text(statement, i+1, [temp UTF8String], -1, SQLITE_TRANSIENT);
  }
  success = sqlite3_step(statement);
 sqlite3_finalize(statement);
  if (success == SQLITE_ERROR) {
   NSLog(@"Error: failed to insert into the database");
   return NO;
  }
 }
 sqlite3_close(database);
 NSLog(@"dealData 成功");
 return TRUE;
}

- (void)dealloc{
 [path release];
 [super dealloc];
}

@end

在此类中将查询写成了一个方法，增、删、改写成了一个方法。
调用起来都灰常简单：

增
NSArray *paramarray = [[NSArray alloc] initWithObjects:@"Miles", @"28", @"69", nil];
NSString *sql = [[NSString alloc] initWithString:@"INSERT INTO t_test (name, age, score) VALUES (?, ?, ?)"];
[self dealData:sql paramArray:paramarray];
[paramarray release];
[sql release];

删
NSArray *paramarray = [[NSArray alloc] initWithObjects:@"2", nil];
NSString *sql = [[NSString alloc] initWithString:@"DELETE FROM t_test WHERE id=?"];
[self dealData:sql paramArray:paramarray];
[paramarray release];
[sql release];

改
NSArray *paramarray = [[NSArray alloc] initWithObjects:@"Miles", @"30", @"2", nil];
NSString *sql = [[NSString alloc] initWithString:@"UPDATE t_test SET name=?, age=? WHERE id=?"];
[self dealData:sql paramArray:paramarray];
[paramarray release];
[sql release];

查
NSString *sql = [[NSString alloc] initWithString:@"SELECT * FROM t_test WHERE score>0"];
[self selectData:sql resultColumns:4];
[paramarray release];
[sql release];

点击此处下载示例。