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我此刻要應(yīng)用SQLite3.0創(chuàng)建一個(gè)數(shù)據(jù)庫(kù)，然后在數(shù)據(jù)庫(kù)中創(chuàng)建一個(gè)表格。
起首要引入SQLite3.0的lib庫(kù)。然后包含頭文件#import
【1】翻開(kāi)數(shù)據(jù)庫(kù)，假定沒(méi)有，那么創(chuàng)建一個(gè)
sqlite3* database_;
-(BOOL) open{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *path = [documentsDirectory stringByAppendingPathComponent:@"mydb.sql"];
NSFileManager *fileManager = [NSFileManager defaultManager];
BOOL find = [fileManager fileExistsAtPath:path];
//找到數(shù)據(jù)庫(kù)文件mydb.sql
if (find) {
NSLog(@"Database file have already existed.");
if(sqlite3_open([path UTF8String], &database_) != SQLITE_OK) {
sqlite3_close(database_);
NSLog(@"Error: open database file.");
return NO;
}
return YES;
}
if(sqlite3_open([path UTF8String], &database_) == SQLITE_OK) {
bFirstCreate_ = YES;
[self createChannelsTable:database_];//在前面完成函數(shù)createChannelsTable
return YES;
} else {
sqlite3_close(database_);
NSLog(@"Error: open database file.");
return NO;
}
return NO;
}
【2】創(chuàng)建表格
//創(chuàng)建表格，假定有五個(gè)字段，（id，cid，title，imageData ，imageLen ）
//詮釋一下，id為表格的主鍵，必須有。
//cid，和title都是字符串，imageData是二進(jìn)制數(shù)據(jù)，imageLen 是該二進(jìn)制數(shù)據(jù)的長(zhǎng)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】向表格中拔出一筆記錄
假定channle是一個(gè)數(shù)據(jù)布局體，保管了一筆記錄的內(nèi)容。
- (BOOL) insertOneChannel:(Channel*)channel{
NSData* ImageData = UIImagePNGRepresentation( channel.image_);
NSInteger Imagelen = [ImageData length];
sqlite3_stmt *statement;
static char *sql = "INSERT INTO channels (cid,title,imageData,imageLen)
VALUES(?,?,?,?)";
//問(wèn)號(hào)的個(gè)數(shù)要和(cid,title,imageData,imageLen)外面字段的個(gè)數(shù)婚配，代表未知的值，將不才面將值和字段關(guān)聯(lián)。
int success = sqlite3_prepare_v2(database_, sql, -1, &statement, NULL);
if (success != SQLITE_OK) {
NSLog(@"Error: failed to insert:channels");
return NO;
}
//這里的數(shù)字1，2，3，4代表第幾個(gè)問(wèn)號(hào)
sqlite3_bind_text(statement, 1, [channel.id_ UTF8String], -1, SQLITE_TRANSIENT);
sqlite3_bind_text(statement, 2, [channel.title_ UTF8String], -1, SQLITE_TRANSIENT);
sqlite3_bind_blob(statement, 3, [ImageData bytes], 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】數(shù)據(jù)庫(kù)查詢
這里獲得表格中一切的記錄，放到數(shù)組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.");
}
//查詢結(jié)果集中一條一條的遍歷一切的記錄，這里的數(shù)字對(duì)應(yīng)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 = [[Channel alloc] init];
if(cid)
channel.id_ = [NSString stringWithUTF8String:cid];
if(title)
channel.title_ = [NSString stringWithUTF8String:title];
if(imageData){
UIImage* image = [UIImage imageWithData:[NSData dataWithBytes:imageData length:imageLen]];
channel.image_ = image;
}
[fChannels addObject:channel];
[channel release];
}
sqlite3_finalize(statement);
}
就簡(jiǎn)單說(shuō)這些吧
