iPhone开发之SQLite的使用

gaohan

　　
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。
　　
DataBaseVC.h

#import <Foundation/Foundation.h>
#import <sqlite3.h>
#import <CoreLocation/CoreLocation.h>
@interface DataBaseVC : NSObject {
sqlite3 *database;
NSString *path;
}
- (void)readyDatabse;
- (void)getPath;
- (NSMutableArray *)selectData:(NSString *)sql columns:(int)col;
- (BOOL)dealData:(NSString *)sql paramarray:(NSArray *)param;
@end
　　
DataBaseVC.m

#import "DataBaseVC.h"
@implementation DataBaseVC
#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 columns:(int)col {
[self readyDatabse];
NSMutableArray *returndata = [[NSMutableArray alloc] init];//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;//一条记录
row = [[NSMutableArray alloc] init];
//NSLog(@"=====%@",statement);
for(int i=0; i<col; i++){
[row addObject:[NSString stringWithFormat:@"%s", sqlite3_column_text(statement, i)]];
}
[returndata addObject:row];
[row release];
}//end while
}else {
NSLog(@"Error: failed to prepare");
return NO;
}//end if
//NSLog(@"returndata：%@",returndata);
return returndata;
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 [returndata autorelease];
}
#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
for (int i=0; i<[param count]; i++) {
NSString *temp = [param objectAtIndex:i];
sqlite3_bind_text(statement, i+1, [temp UTF8String], -1, SQLITE_TRANSIENT);
[temp release];
}
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;
}
@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：

sqlparam = [NSMutableArray arrayWithObject:lineslastdatedate];
sqlstring = [NSMutableString stringWithFormat:@"UPDATE configuration SET LinesLastUpdateDate=?"];
[self dealData:sqlstring paramarray:sqlparam];
增
NSArray *paramarray = [[NSArray alloc] initWithObjects:@"Miles", @"28", @"69", nil];
NSString *sql = @"INSERT INTO t_test (name, age, score) VALUES (?, ?, ?)";
[self dealData:sql paramarray:paramarray];
删
NSArray *paramarray = [[NSArray alloc] initWithObjects:@"2", nil];
NSString *sql = @"DELETE FROM t_test WHERE id=?";
[self dealData:sql paramarray:paramarray];
改
NSArray *paramarray = [[NSArray alloc] initWithObjects:@"Miles", @"30", @"2", nil];
NSString *sql = @"UPDATE t_test SET name=?, age=? WHERE id=?";
[self dealData:sql paramarray:paramarray];
查
NSString *sqls = [NSString stringWithFormat:@"SELECT * FROM t_test WHERE score>%i", 0];
[self selectData:sqls columns:4];