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。