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sqlite数据库检索
1. 数据库检索, 得到某字段下所有值
1 - (NSArray *)selectWithColumName: (NSString *)columName 2 tableName: (NSString *)tableName { 3 if ([self openDatabase] == YES) { 4 5 NSString * selectSQL = [NSString stringWithFormat:@"SELECT %@ FROM %@", columName, tableName]; 6 sqlite3_stmt * stmt = nil; 7 8 int preResult = sqlite3_prepare_v2(_db, [selectSQL UTF8String], -1, &stmt, NULL); 9 10 if (preResult == SQLITE_OK) {11 NSMutableArray * array = [NSMutableArray array];12 13 while (sqlite3_step(stmt) == SQLITE_ROW) {14 [array addObject:[NSString stringWithUTF8String:(const char *)sqlite3_column_text(stmt, 0)]];15 }16 17 sqlite3_finalize(stmt);18 return array;19 } else {20 NSLog(@"check your sqlQuery");21 return nil;22 }23 } else {24 NSLog(@"%@", [self errorWithMessage:@"openDB Failure"]);25 return nil;26 }27 }
2. 通过你存储的模型以及数据表名得到所有的数据
1 #pragma mark - select DB 2 - (NSArray *)selectAllMembersWithTableName: (NSString *)tableName 3 objectModel:(id)object; { 4 if ([self openDatabase] == YES) { 5 6 NSString * selectSQL = [NSString stringWithFormat:@"SELECT * FROM %@", tableName]; 7 sqlite3_stmt * stmt = nil; 8 9 int preResult = sqlite3_prepare_v2(_db, [selectSQL UTF8String], -1, &stmt, NULL);10 11 if (preResult == SQLITE_OK) {12 NSMutableArray * array = [NSMutableArray array];13 14 while (sqlite3_step(stmt) == SQLITE_ROW) {15 16 id model = [[[object class] alloc] init];17 for (int i=0; i<sqlite3_column_count(stmt); i++) {18 [model setValue:[NSString stringWithUTF8String:(const char *)sqlite3_column_text(stmt, i)] forKey:[NSString stringWithUTF8String:(const char *)sqlite3_column_name(stmt, i)]];19 }20 [array addObject:model];21 [model release];22 }23 24 sqlite3_finalize(stmt);25 return array;26 } else {27 NSLog(@"check your sqlQuery and Model");28 return nil;29 }30 } else {31 NSLog(@"%@", [self errorWithMessage:@"SqlQuery error"]);32 return nil;33 }34 }
3. 通过key:value对应关系的字典为数据库查询语句的基础, 得到需要的值
.h文件定义以及使用提示
#pragma mark selectWithSqlQueryDict/* get value with sql statement you must give columName(dict key) = value(dict value) - all string type. e.g dict = { "name" = "xxdbuser", "age" = "19" }; object: model you want 通过包含有你的约束条件的字典、 通过表名称、 你所给的模型、 返回包含有若干模型的数组 */- (NSArray *)selectWithSqlQueryDictionary: (NSDictionary *)sqlQueryDictionary tableName: (NSString *)tableName model: (id)object;
.m 文件实现
1 #pragma mark selectWithSqlQuery 2 - (NSArray *)selectWithSqlQueryDictionary: (NSDictionary *)sqlQueryDictionary 3 tableName: (NSString *)tableName 4 model: (id)object { 5 6 // getAllKeys 7 NSArray * keyArray = sqlQueryDictionary.allKeys; 8 NSString * sqlQuery = [NSString stringWithFormat:@"SELECT * FROM %@ WHERE ", tableName]; 9 10 if ([self openDatabase] == YES) {11 12 // foreach build sqlQuery13 for (NSString * key in keyArray) {14 sqlQuery = [sqlQuery stringByAppendingString:[NSString stringWithFormat:@"%@ = ‘%@‘ and ", key, sqlQueryDictionary[key]]];15 }16 sqlQuery = [sqlQuery substringToIndex:[sqlQuery length] - 4];17 18 sqlite3_stmt * stmt;19 20 int result = sqlite3_prepare_v2(_db, [sqlQuery UTF8String], -1, &stmt, NULL);21 if (result == SQLITE_OK) {22 NSMutableArray * array = [NSMutableArray array];23 24 while (sqlite3_step(stmt) == SQLITE_ROW) {25 26 id model = [[[object class] alloc] init];27 for (int i=0; i<sqlite3_column_count(stmt); i++) {28 [model setValue:[NSString stringWithUTF8String:(const char *)sqlite3_column_text(stmt, i)] forKey:[NSString stringWithUTF8String:(const char *)sqlite3_column_name(stmt, i)]];29 }30 [array addObject:model];31 [model release];32 }33 34 sqlite3_finalize(stmt);35 return array;36 } else {37 NSLog(@"check your sqlQuery");38 return nil;39 }40 41 } else {42 NSLog(@"%@", [self errorWithMessage:@"openDB Failure"]);43 return nil;44 }45 }
4. 错误信息的输出
1 #pragma mark - errorMessage2 - (NSError *)errorWithMessage:(NSString *)message {3 return [NSError errorWithDomain:@"XXDB" code:sqlite3_errcode(_db) userInfo:[NSDictionary dictionaryWithObject:message forKey:NSLocalizedDescriptionKey]];4 }
ok 今天就到这里。 数据库是数据持久化最常用的办法。 一定熟练掌握用户的各种需求实现的办法
sqlite数据库检索
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